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Wednesday, January 07, 2009

FAN DEATH IS REAL

Dear Korean,

Last year when I was in Korea I learned about the phenomenon “Fan Death”, which quite astonished me. How could a simple fan kill a man while he's asleep in a room with windows closed? In other words, why must the window be open when you're running a fan the whole night?

Donghun

Dear Korean,

Do you have any idea where the myth of Korean "Fan Death" might have originated from? And why practically all Koreans to this day still believe in it so vehemently?

Sandra P.

Dear Donghun and Sandra,

The Korean wishes to start the New Year off with a bang, and what better topic than the fabled Fan Death to do that?

Let’s take first things first. Here is the definition of Fan Death: Koreans believe that during summer, in an enclosed room (i.e. all doors and windows shut), an electric fan running directly on your body could kill you while you sleep. Elderly, children, and people sleeping drunk are at the greatest risk. To prevent this, Koreans either open a window a crack, or use a button on the fan that makes it either oscillate or shut off after a certain amount of time.

How does a fan kill? The most common explanations that Koreans generally offer are two. The most prevalent explanation is that the fan used directly on your body causes suffocation, because the fast-moving air around your face makes inhalation difficult. Alternatively, some Koreans also offer that breathing through skin constitutes a significant proportion of breathing, and the fast-moving air caused by the fan makes the skin-breathing difficult, leading to suffocation.

The other prevalent explanation is hypothermia, i.e. abnormally low body temperature. The idea is simpler – fan lowers body heat through dehydration, ultimately to the extent that it could kill.

If these explanations sound ludicrous, that’s because they are.

The Korean has had a complicated relationship with Fan Death. The Korean definitely believed in Fan Death while living in Korea. There was no reason not to – everybody believed in it, and the media reported a case of fan death around once or twice every summer. (Like this article, for example.)

Then, once emigrated to America, the Korean was astonished to learn that only Koreans subscribe to this idea that fans could kill. Once the Korean thought about the explanations he had heard, it was plain that they made no scientific sense. As the Korean went through his self-hate phase (because to varying degrees, all Korean Americans go through this at some point in their lives,) he thought fan death was a prime example of how Korea remained primitive.

Here is the science of how a fan could kill. Remember the conditions under which Koreans say Fan Deaths happen – summer (=heat), enclosed room, fan directly on the body. An electric fan cools your body in two ways: by pushing cooler air onto your body, and by allowing your sweat to dry rapidly and take away heat in that process.

But clearly, the fan does not generate the cool air on its own, unlike an air conditioner. And eventually -- especially if you are a passed-out drunk who is already somewhat dehydrated from the alcohol -- your body will run out of water to turn into sweat. So what happens when it is very hot, but the entire room is enclosed such that no cool air comes in from outside, and you have no more sweat to cool your body with?

Basically, the entire room turns into a gigantic turbo oven. Turbo oven is a conventional oven that has a fan inside that continues to blow air onto the food. This oven is known to cook at lower temperature than a regular oven, yet cook more quickly. Similarly, in a heated room without an outside source of airflow, very hot air is constantly pushed directly to your body, which is a far more effective way of raising your body temperature rather than “baking” in hot air. If you get enough of this, you would die – of hyperthermia, or abnormally high body temperature.

So Korean people had it right after all – fans can kill. They just tend to give the wrong reason.

Common objection to this explanation is: in such an oppressive heat, the person would have died from hyperthermia anyway, with or without the fan. This objection underestimates the effectiveness of the fan raising the body temperature.

Humans maintain body temperature by developing a thin layer of air around their body that is similar to their body temperature. Because air is a poor conductor of heat, the layer of air around the body adapt very slowly to the temperature of the surrounding air, maintaining steady temperature.

This fact can be proven in several ways. Cold days with strong wind feel much colder than cold days without any wind, because the wind takes away the air layer around the body. Dressing in layers is more effective to keeping warm than dressing in a single thick outerwear. You can do fine wearing only a T-shirt and jeans in 70 degree Fahrenheit air, but you would get really cold wearing T-shirt and jeans in 70 degree Fahrenheit water, because water is a much better conductor of heat. To prevent losing heat, divers wear a wetsuit, which limits the amount of water touching the body, essentially creating the same thermal layer with water.

This method of temperature maintenance works the same way in heat. Although body temperature above 104 degree Fahrenheit (40 degree Celsius) is life-threatening, humans can go on living for hours in temperature much higher than that. How? Humans sweat, and when the sweat drops evaporate, the air around the body cools because of the evaporation. As long as the cool layer of air surrounds the person, the person’s body temperature remains stable.

But if the fan runs directly on the body, that layer of air is taken away, replaced by the same hot air in the room. The room temperature might remain the same, but the body will feel hotter. To compensate, the body would produce more and more sweat, but the sweat would quickly evaporate without offering any protection to the body because the fan is constantly blowing hot air. At some point, the body would run out of water to produce sweat. And starting from this point, the body temperature would rise dramatically.

How dramatic? Turbo ovens can cook the same amount of food at the cooking temperature that is about 50 degree Fahrenheit (30 degree Celsius) lower than a conventional oven. Once the human body loses the ability to regulate heat, it is just like a piece of meat in a turbo oven. In fact, for the purpose of avoiding hyperthermia, human body is worse than a piece of meat -- because it internally generates heat. Keep in mind that Korea’s summertime routinely hits 90 degree Fahrenheit (around 31 degree Celsius). This means that although the room’s air temperature is 90 degree Fahrenheit, with a fan on, your body is cooking at the same rate as being in a room with 140 degree Fahrenheit (61 degree Celsius), plus the rising body heat that is not mitigated by the evaporating sweat. Needless to say, this would kill you – especially so if you do not have a body that controls temperature well, i.e. drunks, children, or elderly.

Don’t believe the Korean? Would you believe the U.S. Environmental Protection Agency? This pamphlet from the EPA, at pages 49 and 51, clearly states the hazard of using portable electric fans during high heat. It specifically says “Portable electric fans can … increase the circulation of hot air, which increases thermal stress and health risks[,]” and “DON’T use a portable electric fan in a closed room without windows or doors open to the outside.”

Dr. Lawrence Kalkstein from the National Weather Service

Or how about a climatology professor who works for the National Weather Service? In an interview with NPR about extreme heat warning system, Dr. Kalkstein specifically mentions the danger of fans in a hot, enclosed room (At 13:45 mark): "One piece of advice we tell them not to do is to sit in front of a fan in a hot apartment because it has a convection effect."

-EDIT 2013/08/11- Or how about the Weather Channel?

A few points to conclude the post.

1. Why are Koreans so concerned about fan death (aside from the fact that it is real)?
Answer: Why not? We are talking about death here. People around the world engage in all kinds of silliness to cheat death. For example, recently the most emailed New York Times article for a few days in a row was about the dangers of “third-hand smoking”, i.e. the health risk posed by cigarette residue remaining in the smoker’s furniture, clothes, or hair, long after the act of smoking was done.
The Korean does not want to diminish the danger of smoking, or even second-hand smoking. But the Korean’s reaction to this article was: Are these people serious? The article says nothing about whether “third-hand smoking” has a measurable effect on health – it simply says there are unhealthy particles, and people don’t know about them. But bad particles are everywhere, with or without previous smoking! How can the article be convincing without talking about some measure of how much bad particles one could ingest through third-hand smoking? Yet the Korean will guarantee that sooner or later, the term “third-hand smoking” will be used by a concerned legislator as she pushes to make more public places non-smoking.

2. Does getting the cause for Fan Death wrong mean Koreans live without critical thinking?
Answer: Of course not. Fan Death is a miniscule part of Korean people’s lives. All they need to do to prevent it is to open the window or press a button. Simply put, Fan Death is not something Korean people think much about.
For a similar example, to this day, there is no scientific consensus about the health benefits of drinking red wine. In fact, the idea that drinking alcohol helps your health is utterly counterintuitive. Yet when Americans say red wine is good for your health, other Americans simply nod in agreement and move on. It is not a point worth debating. Drinking red wine over, say, beer, does not take much effort. And if there is health benefit to it, true or not, it’s simply a bonus.
The same with Fan Death. Unlike the health benefits of red wine, Fan Death is real. And if all it takes to prevent it is as minor as pressing a button, why bother thinking hard about it? Koreans have no urgent reason to debate what the precise cause of Fan Death is.

3. The Korean would place the blame on the misunderstanding about the cause of Fan Death to the Korean media. Korean media has been careless reporting cases of Fan Death. Recently, Korean media itself is realizing this point. According to a Dong-A Ilbo article, there simply has been no scientific effort to prove Fan Death, even in cases where the fan was supposed to be responsible. There have been no papers on this topic, and no autopsy performed on the person who supposedly died from Fan Death.
The Korean will reiterate: Fan Death is real. The causal mechanism is causing death is very clear; Koreans who warn of Fan Death warn of the exact conditions under which such causation would occur; and it is very plausible that such causation will in fact occur in Korea. However, the Korean will say this: Most likely, not all cases of Fan Death reported in Korean media are truly Fan Death.

-EDIT 12/7/09- If you are an expat in Korea and are about to comment on how Fan Death is still impossible, please read this post from Ask the Expat regarding Korea Derangement Syndrome first before commenting.

Got a question or a comment for the Korean? Email away at askakorean@hotmail.com.

This is going to be a very popular post. I commend you on a very logical, well-thought-out post. I have to admit that I won't approach the subject with as much ridicule as I once did (though still some).

You really created a plausible explanation for fan death. That's all I've ever asked for. The convection oven example is beautiful. Additionally, your acknowledgment and rationalization of the minuscule odds makes it a difficult argument to counter. Of course, in doing so, you've really re-defined fan death, as previous definitions offered (anywhere as far as I can tell) have not put forth the same rationale. With that in mind, I might say that you didn't justify the existence of fan death, but rather high temperature, closed, circulatory air flow environments death :)

Your description of how turbo fans work is a little off as well. They don't work by blowing hot air on the food (or people in this case); they work by circulating air and creating even heat in the oven (room). This could also work in your rationale's favor as many Koreans sleep close to the floor where the air is cooler. Circulating air would increase the temperature of the air close to the ground.

It's been a while since I broached the subject with Koreans. I eventually realized, as you mentioned, that it was simply a non-issue and therefore why bother with it. However, it's still an excellent topic for critical analysis if one has students who are capable of addressing it. Your piece is a great balance to the reams of anti-fan death pieces.

I find this very interesting, but given the size of the at-risk population, namely people drinking, and the apparently huge number of foreign commentators who recreate this very situation in order to mock it (having myself survived, many times over, such conditions, whilst slumbering in a drunken stupor) why aren't there more cases? I do recall reading an article in either the Herald or the Times (of Korea) which stated that (in the author's opinion, who was Korean himself) he worried that fan death was used to ignore things like aneurysms, heart failure, and other more common health-related causes of death which deserve (in the author's opinion) greater attention than fan death as popularly conceptualized. I wonder if the people here (this postmodern world makes it so difficult to retain any credibility or accuracy whatsoever with such a vague and ambitious catchall word like 'Koreans') are themselves divided about the meaning of fan death: a Korean friend of approximately my age said in her opinion/experience, fan death was a euphemism used by both family and the media in order to cover up a more shameful sort of death, like suicide or liver failure (as related to alcohol poisoning). But I'm glad you took the time to explain the process in a more step-by-step fashion.. and while I'm not thoroughly convinced just yet, you certainly give more substance to mull over than the average translated article. Oh, and about the wine thing: I've read numerous studies about the benefits of red wine, but there's a catch: the benefit is from a certain chemical particular to red grapes, hence the benefit which wine gives is also available in grapes. I think people have simply extended this to wine since those chemicals are found there as well but wine is more fun to consume than grapes. And I wish I could name the chemical off the top of my head, just to give this thought greater credence, but it has been a while since I read one of those articles. I imagine I can find it somewhere in the NYT "Well" blog.(Previous post was deleted due to a grammatical error.)

Just for those who are interested: the following article discusses reservatrol, a chemical found in the skin of red grapes which is the focus of studies examining the health benefits of red wine/grapes. http://www.sciencedaily.com/releases/1997/12/971219062019.htm

I must say I love your blog, and this post gives quite a bit of information about the issue. Thanks for your well-thought-out argument and excellent research.

My only concern is to have Koreans in general make the 'we told you so' argument, then extend that to anything that's been controversial. 'We were right about fan death, we're right about this too', and so on. Perhaps by next summer the issue will become more known about and less of a issue as a result.

Has Mythbusters done a show on this yet? It would be a fun show to watch - I can just imagine using their jello-like man to show how he cooks in the very hot room...

roboseyo wishes to salute the Korean's brave stance for truth about fan death, and wonders why Koreans were so upset about mad-cow beef, when the much more serious dangers of cigarettes and electric fans were being exported from america to Korea by the boatload.

for more reading on ANOTHER kind of fan death...http://en.wikipedia.org/wiki/Selena#Death

you need to revisit the section in the EPA guidebook, which states that this is only in cases of extreme heat, which the EPA defined in the same section as exceeding 99F (just over 37C) which is within 3C of the highest temperature ever recorded in Korea (40C in Daegu way back in 1942). Not only that, it would have to reach this temperature INDOORS and the people at risk would have to become dehydrated to a substantive degree. In essence, this is something *possible* but so unlikely and requiring such particular circumstances that I'm essentially calling this explanation for fan death in Korea busted. I'm fully ready to believe that "fan death" covers lazy postmortem exams and causes of death that families don't want publicized, but not the turbo oven in my one room explanation.

Yeah, I gotta say that in terms of scientific "evidence," it is greatly lacking. There are too many variables and highly unlikely situations to account for. Like Gomushin Girl essentially says, it would have to be the perfectly wrong conditions. Not only that, but the person would have to be unconscious because animals wake up when the environment goes beyond a certain comfort zone.

You're definitely perpetuating a poorly supported myth similar to, "don't drink water while you eat." Which is bogus as well.

It seems like this is a great way to kill someone and get away with it in South Korea. Suffocate them in an enclosed room and turn on a fan before leaving. I wonder just how many fan deaths are really murders in disguise?

Oh, yeah. Wrapping the cord around the neck is also fan death, but you might actually get an officer who takes their job seriously with that one.

Can't really say -- the information has been accumulating for a few months, intermittently.

Dan,

Thanks for the correction on the turbo oven.

Chris in SK,

As far as I know, Mythbusters did not do a show about this yet. Not for the lack of submission though -- apparently there are more than 430 requests for fan death.

Gomushin Girl,

You are referring to p. 37 of the pamphlet, but you misread it.

First, according to the EPA, Excessive Heat Event (EHE) cannot be defined by a set number. Because of regional differences in weather pattern, dynamic definition of EHE is necessary. Pp. 9-10 of the pamphlet describes this necessity.

The necessity for a dynamic definition is also demonstrated in the chart on p. 15, describing EHE-attributable mortality rate in the U.S. Although Phoenix, AZ is on average significantly hotter than Providence, RI, EHE-attributable mortality rate at Phoenix is zero, while the same number at Providence is 4.14.

Second, the language you cite at p. 37 does not talk about air temperature of 99 F -- it talks about heat index temperatures of 99 F. Heat index temperature is a combination of air temperature AND humidity.

Heat index values are shown on a table on p. 16. Heat index of 99F can occur when the air temperature being 90F and humidity at 60 percent. This is easily achievable during summer in Korea. At 95F air temperature, only 40 percent humidity is required to have the heat index of 98F. Conversely, at 85F air temperature, 80 percent humidity (again, very achievable during summer in Korea) can produce heat index of 96.

Because of this, the pamphlet states is advice clearly at p. 51 - "DON'T direct the flow of portable electric fans toward yourself when room temperature is hotter than 90F."

One thing that the Korean did not discuss in the post is -- as much as Koreans stick to the idea of Fan Death, expats in Korea stick to the idea of disproving Fan Death. It seems that Fan Death has achieved the status of the weird kid at school: all the cool kids make fun of him, so we all must stick to mocking him, regardless of reason.

Here, the Korean presented a perfectly scientific explanation for Fan Death. The Korean also clearly stated that most likely, not all cases of reported Fan Death are actually Fan Death. But in trying to dispute this, the people who regard themselves as logical and scientific for disputing Fan Death offer illogical and unscientific counterpoints.

Case in point: The James's idea that because the event is so unlikely that it must be false. That idea is utterly illogical.

First, Fan Death in Korea is a rare and unlikely event. Even including the "false positives" reported in the media, Fan Death is not reported any more than once or twice every summer.

On the other hand, the preconditions leading up to Fan Death are completely likely. Korean weather can easily produce excessive heat events; many homes use only electric fans without an air conditioner; because of various pests during summer (esp. mosquitos,) Koreans often keep their room windows shut. On top of that, Koreans are prodigious drinkers, which leads to dehydration (thus reaching the point of body temperature non-regulation faster) and passing out (which enables staying asleep while hyperthermia progresses.)

Like the Korean said in the post, he was a skeptic of Fan Death as well. But the Korean has this base belief: if a mass of people believe in something, something is either true to a certain degree, or people do so for a good reason (i.e. not "stupidity").

Therefore, once the Korean found a scientifically plausible explanation for Fan Death, and realized that each precondition leading up to Fan Death is not only likely in Korea but also consistent with what Korean people believe, the Korean was ready to believe that Fan Death is real.

At this point, the only possible way to deny the existence of Fan Death is this: because there has not been a controlled study on the topic, I am not ready to believe it. If that's your stance, the Korean has no problem with that -- more power to you. The Korean will note that much of what we take to be true is based not on controlled study, but on plausible inferences. (e.g. global warming.)

I understand what you're saying, and as a research biologist I apologize if it seemed that I claimed it as false. My point is simply that "Fan Death" is so highly improbable that people shouldn't ever be concerned by it. It still does require the perfectly wrong conditions.

Statistically vending machines kill more people every year, but we don't avoid them. You're chances of slipping in the shower are exponentially higher than "Fan Death."

I personally find these types of articles annoying because there are many many more common things in this world that pose a greater threat. To give this kind of topic this much attention is just weird. I think it bothers me on another level because my parents wouldn't let me sleep with a fan on either.

We don't avoid vending machines or showers, but we *do* take precautions.

For example, vending machines have warning signs on them, explaining that you shouldn't tip them over or you may be crushed and killed. The floors of shower recesses are textured to reduce slipping, and you can buy non-slip bath and shower mats in pretty much every mall on earth.

Many things present risks, and as we become aware of those risks we act to mitigate them. The existence of other, known risks which we already mitigate is not a reason to avoid mitigating a newly identified risk.

The Korean can get behind that sentiment. For a similar example, people are afraid of shark attacks to a disproportionate degree of the actual danger -- falling coconuts are known to cause more deaths and injuries than sharks per year.

The Korean only devotes the effort to explaining Fan Death because of the countervailing effort -- that is, the visceral and total denial of the existence of Fan Death, and the nonstop attempt at mocking Koreans for believing in Fan Death. Sure, Fan Death is an unlikely event, and overall it is a little silly to be preoccupied by it. But Fan Death does exist, and Koreans are no stupider than any other people for believing in it. That's all the Korean wanted to show through this post.

donghun here. Thanks for the post. Glad to know finally an answer. Truly expat bashing/making fun of over events like "Fan Death" is truly poor, remember every nation has its own kind of fan death event which is for foreigners strange.

I think your expert testimony you have provided is very persuasive, and I'm inclined to believe that there is a danger to fans in extremely hot enclosed rooms. However, as far as your actual explanation of the phenomenon, I think you have made a pair of unwarranted assumptions/logical errors. They may be true but I don't think you've proven them adequately:

1) The warm layer of air around the body in cold temperatures is the same method of temperature maintenance in heat, and with this layer broken up by a fan, sweating would evaporate quickly without offering any protection.

You don't provide any cite for that other than assuming that because it works for cold temperatures, it must work the same for hot, but that is not obvious to me. Furthermore, while that may be a component of the cooling effect of sweating if true, evaporative cooling causes an actual decrease in the temperature of the fluid, and while your sweat may cool the air around you, it will also cool the body directly.

2) Because turbo ovens can cook at temperatures 50 degrees lower, that must mean fans can increase any temperature by 50 degrees. I am unconvinced that the turbo oven effect can create any such effect to that magnitude at room temperature. Is there reason to believe the 50 degree increase is not proportional to the high temperatures already inside an oven? So would using a fan in a 70 degree room be equally dangerous to sitting for a prolonged period in a 120 degree room?

I get where you're coming from now. When I read the article though it sounds like you support the idea that people should fear "fan death." It feels like you're legitimizing its dangers.

Koreans aren't any dumber than other cultures for believing that this is a real threat, but that doesn't mean they aren't dumb for believing it. It's just that everyone else is just as dumb, and that's okay.

Ah, one of my favorite parts of Korea...Fan Death! Seriously, thanks for the great article. Let's not forget that many Western cultures also have weird myths and unjustified fears that are constantly propagated despite scientific evidence to the contrary (many urban legends or religious prohibitions, for instance). Although none are probably as quite colorful as Fan Death.

Fan Death. I've always thought it would be an awesome name for a heavy metal band.

1. About sweating -- You make two points about sweating: (1) "thermal layer" may exist in cold situation, but not in hot situation; (2)sweating directly lowers the body heat.

To the first point, the Korean does not know what to say. "Cold" and "hot" are merely two different degrees of temperature. The fundamental physics of heat conduction by air does not change with temperature.

As to the second point, the Korean agrees that sweating would directly lower body heat, but that ultimately does not affect the analysis. Body temperature would rise up dramatically after the body can no longer produce sweat, through dehydration. It is possible that the body temperature would dip as long as the fan blows the sweat dry, but once that stops, the body temperature would rise, causing hyperthermia.

2. About the "turbo oven" effect -- your objection is a good one. But even if a fan in the room does not, in effect, raise the temperature by 50F, the Korean thinks the analysis is unaffected. Body temperature of 104F is fatal, and 104F is not a long way to go from 90F-plus room temperature.

The Korean will concede that a controlled experiment would be necessary to definitively prove Fan Death to be true. But the Korean believes that the hyperthermia theory is correct because (1) the causal mechanism is clear; (2) the preconditions leading up to Fan Death is, while unlikely, perfectly plausible, and; (3) the preconditions leading up to Fan Death is identical to what Korean people perceive as dangerous, and also consistent with Korean media report as Fan Death.

thanks for clarifying the math behind EHE math . . . but I did not misread the section - unlike you I don't seem to have the leisure to plow through the entire EPA manual. And again, the problem is that the theoretical possibility is still so incredibly unlikely that it is essentially nil AND more importantly for your claim that fan death is real is that there is apparently not a single actual death attributed to this problem. Fan Death is, at best, a real possibility, but that does not equal reality. The problem returns again to the fact that the basis for the claims of fan death that foreigners in Korea find so ludicrous are, in fact, still ludicrous.

"Among the substances in third-hand smoke are hydrogen cyanide, used in chemical weapons; butane, which is used in lighter fluid; toluene, found in paint thinners; arsenic; lead; carbon monoxide; and even polonium-210, the highly radioactive carcinogen that was used to murder former Russian spy Alexander V. Litvinenko in 2006. Eleven of the compounds are highly carcinogenic." From the NYT article about 'third-hand smoke.' It seems that there are casual elements directly addressed in this article, such that the mechanics which might give rise to a health concern are clearly illustrated. In that way I don't believe it's accurate to draw any parallel between the NYT article and fan death (nor accurate to call the belief in benefits of drinking red wine a myth, being as it has been demonstrated by numerous independent laboratories according to the scientific method. Which begs the question, why has no laboratory in Korea taken this on?)

Might it not be beneficial to forget about 'fan death' and talk directly about the mechanism, i.e., hyperthermia and conditions which predispose an individual to hyperthermia? It seems the press would retain a great deal more credibility if they addressed the issue as such, and by doing so informed their readers as to the mechanics of the situation. It would go a long way to benefit both Koreans' understanding of commonplace myths (not that fans kill, but rather contribute to a situation which also might arise is circumstances not involving a fan, say simple dehydration or sun exposure) and also help to diminish the language/culture gap experienced by foreigners living in or visiting Korea as well as provide a better basis upon which such questions might be answered. And plenty of people ave their superstitions and scientific misattributions, but no one in this day and age is expected to take seriously, say, someone who cites an encounter with a black cat for the loss of their job or relationship though such people still exist (thankfully as a minority).

Especially since Korea as a country seems to value science so highly, at least as an area of academic expertise. I would expect such a thing to have a clear cultural impact as well, seeing as how the most superstitious people I know personally, or those who erroneously attribute casual components, or those who most confidently create 'backronyms,' or who most enthusiastically support conspiracy theories are those who have the least amount of formal training in whatever field their enthusiasm takes hold of. In my mind, the grievance is common: intellectual dishonesty born out of ignorance or a lack of curiosity as to ascertaining the true causes of a situation. And that perhaps is the real crime of perpetuating urban myths, whether it's fan death (as separated from the hyperthermia you've discussed, which does have other sources as well and is itself a source of great concern during hot months, particularly to the young and elderly) or bad luck and broken mirrors. Or, to give a nod to the fool about to depart a high national office, receiving military intelligence during prayer.

But being human, I suppose no culture will ever get past this sort of thing, seeing as how people who so delightfully misattribute causes seem to get a warm and fuzzy feeling of nostalgia and certainty from repeating whatever the hell it was their grandparent told them when they were young.

I noticed that you linked to my MH post about fan death reports in the Korean media yet missed the post about the climatology professor's visit to Seoul, from which you obtained the links to his university webpage and NPR story.

Sure, the laundry list of toxins is intimidating, but how much toxin are we talking about? In the age of polluted air and polluted water, everything we take in has toxins to some degree. Just how much toxins does third-hand smoking provide? NYT article is silent on that.

The Korean agrees with your other points, except this part: "...help to diminish the language/culture gap experienced by foreigners living in or visiting Korea..." The Korean does not think the Korean media owes any duty to explain Korea to foreigners. If foreigners do not keep an open mind and accept different possibilities, however outlandish they may sound, it's their problem.

Sonagi,

The Korean sincerely apologizes. The point in the post about ridiculing Korea was not meant to be directed to you or Robert -- it was directed to the commenters of the posts in MH. The Korean should have been clearer. Also, HT should have been made as to the NPR story -- although the Korean would note that he is the one who provided the initial info leading to the post about Dr. Kalkstein. At any rate, sorry about that.

I apologize for not phrasing that statement very well. What I meant to convey was the sentiment that the popular media (including such publications as the NY Times, which oscillates between very informative and utterly propagandist, compare Olivia Judson's evolution blog to Tara Parker-Pope's Well blog) has a responsibility to inform the public responsibly. I simply see the fan death phenomenon as an outgrowth of irresponsible reporting, and perhaps the third hand smoke is an an example of this as well. The American media serves the purpose (or should, and does on its better days, and on its lesser days simply invigorates and justifies negative stereotypes about Americans, see Fox News) of not only informing the American public but informing the rest of the world as well though a well-informed public. I'm just for better information all around, where native media uplifts and clarifies the understanding of the public they serve, thereby enabling that public to bring its case, culture, and ethos to the world with a minimum of misunderstanding. There's a critical absence of science in media generally, but why avoid criticism simply because all involved have failings? Isn't it more profitable to be self-critical but additionally question the assumptions of others as well? I sure hope that some kid in Korea gets into geology and looks at the percentage of people in the US who believe in "young Earth" creationism and thinks to himself, "WTF?" Every country and culture needs a critical eye, and it's difficult to be more objective being from the culture or country in question. Sometimes the act of trying to explain or justify one's beliefs to another who has been raised without the same beliefs is a window to self-reflection. That's all. And yes, I do think that in some respect we're all cultural emissaries who bear a responsibility similar to the one which here I've ascribed to the media. I've done my best to explain zillions of questions from people I've met here about America, whether they're Korean or Scottish. I do think we've all got to do our part. I mean, why do you think this blog is so popular? People have lots of questions and lots of opinions. And until we communicate these things in a forum like this, people unaccustomed to 'fan death' mock it, and those who've never thought twice about it continue to say things like "well, fans destroy oxygen." (Which is in fact something I was told. I think something was lost in translation. I hope.) Sorry for the verbosity.

i may be missing something here, so if i am i apologize, but how often does the heat index really get that high at night? it seems to me that it would be an extremely rare occurence, if ever, that it climbs that high between the hours of, say, 9pm and 9am. further it seems like as the index falls during this period, it should gradually relieve the stress on the body and allow increasingly normalized perspiration. again, i'm going to admit my ignorance here and that the korean and many of the people commenting seem to know more about the subject than i do, so really this is more of a question than a challenge.

Flip to p. 108 to see the info from Daegu, one of the hottest cities in Korea. The mean relative humidity during July and August was around 72~73 percent -- and the Korean knows for a fact that 80 percent humidity occurs quite frequent in that city, although the report does not list the highest humidity. (Because obviously, the highest humidity is at 100 percent, when it's raining.)

The air temperature is revealing. From May through September, there were at least one day in each month that were 90.6F, 91.4F, 95.9F, 97.5F, and 91.4F. (Converting from Celsius.) Also in August, the mean highest temperature of the day for all 31 days was at 89.6F.

At the air temperature of 90F, the heat index is 105F if there is 70% humidity, and 113F if there is 80% humidity. So the heat index in Daegu averaged around 105F in August, occasionally spiking up to 113F and beyond. And at least one day in August, the heat index was over 130F, assuming 70% humidity.

But you are correct -- these heat indices should come down at night. However, the main component of Fan Death is an enclosed room. If there is no cooler outside air introduced into the room in which the heat index was at 130F, it is completely possible that the room remained over 99F heat index through the course of the night.

It seems to me that "Fan Death", as it is used in the Korean media, and death by very high temperatures in enclosed spaces, which is widely recognized, should be seperate and distinct. A fan might be some contributing factor, but let's face the fact that it's heat death, not fan death.

The Korean would note that the term "Fan Death" is not a Korean term; it is a term that English-speaking Korean observers made up to describe Korean people's general belief about fan being a contributing factor to death caused by hyperthermia.

In fact, Korean people's belief is quite specific. They always speak of high heat, enclosed space, and the fan directly running on the body all night for death to occur. Non-Koreans hearing this concept fixate on the fan part, but Koreans themselves know better.

okay thanks for the explanation. personally, i don't really have any particular vested interest in the veracity of fan death or lack there of, i just find it intriguing. and, your explanation seems quite reasonable. i do have just one more thing to say about your last comment, though, and that's that i one day got to talking about 'fan death' with one of the other teachers at my middle school, who was horrified to learn that i slept with the fan on nearly every night of the year. she asked why i would ever need to sleep with a fan on when i had air-conditioning in my apartment. i explained that it was simply habit and i found the white noise comforting and also concealing, since my 19 year-old live-alone neighbor enjoyed singing 'ballads' as he bathed at 5:30am nearly every morning. i then asked her under what circumstances it would be acceptable to sleep with a fan on, at which point she replied 'with the window open'. i pointed out the unlikeliness of that occurring since it was, at the time, around late november or early december, and she then reasoned that no one needs to sleep with a fan on in the winter and i had better not expose myself to such dangerous circumstances for the sake of comfort. i reminded her about the singing, and she said we should find another solution. the next day i arrived at school to find a pair of foam ear plugs on my desk. apparently word quickly spread because over the next few days i was cautioned by several other teachers, with one asking me how my parents could have 'never taught me about that'.

What I don't agree with is that your basing your assumptions on a lot of ifs. Generally, the human body is well adept at adjusting and maintaining homeostasis even in extreme temperatures. So is it possible that if your in a small enough room, with the windows closed, with it being 90 C, with the fan positioned in such a way that it blows on the entire/majority of body's surface area (meaning likely you will not have any night wear on), with a large enough fan in comparison to room and person, and if they stay in that room long enough, and if they dehydrate without drinking additional water at night. Additionally, a turbo oven is based on multiple fans that circulate air uniformly for such a small volume. Most people utilize one. If your sleeping on a bed or even the floor, half of your body is also transferring heat away and not being exposed to the hot air.

My point is that almost everything is possible in science if you manipulate the conditions correctly. But what is the probability here? If your entire point is rationalizing that Koreans have some sort of scientific justification behind their illogical beliefs, then your point is grasping for straws at best. To clarify, my point on being illogical was that for the number of possible cases of fan deaths that occur in equation with the fear involved does not match.

At the end of the day, every country has dumb illogical beliefs that stemmed from urban folklore or very rare instances. But they accept it as that, no need to justify that. In fact, it only further perpetuates the stupidity and pride involved in rationalizing the irrational.

"...and when the sweat drops evaporate, the air around the body cools because of the evaporation. As long as the cool layer of air surrounds the person, the person’s body temperature remains stable."

In actuality, the skin that is "wet" experiences cooling because of the phase change from liquid->gas of the sweat (easier to draw heat energy from the skin than the air around it). In a room w/ humidity <100%, a fan circulating air would contribute to additional cooling (not heating), since the air immediately around the body that is of a higher humidity because of the evaporation would be replaced by less humid air, improving the rate of evaporation. This circulation of air would continue to aid in cooling until the entire room was at 100% humidity.

The point is that because of the fan, the sleeping person must constantly generate sweat, accelerating the dehydration. If there was no fan, the person would develop a layer of cool air around his body through the evaporated sweat, and dehydration would be prevented.

Peter,

Koreans do have a scientific justification in being worried about Fan Death. The Korean showed that scientifically, Fan Death is real. The Korean also showed that each element necessary for Fan Death is present in Korea -- therefore, at least some of the reported cases of Fan Death in Korea are really, truly Fan Deaths. The Korean even put a caveat that there may be cases of false positives.

The Korean thinks that your point is that Koreans do not have the statistical justification in being concerned about Fan Death, because Fan Death is a rare event. Well, go back and read the post again. The Korean explicitly said Fan Death indeed is a rare event. The Korean also explicitly said that Koreans only ponder about Fan Death about as much as Americans ponder about the health benefits of red wine. In other words, Korean people's concern over Fan Death is perfectly proportional to the statistical danger of Fan Death. There is nothing irrational about what Koreans do. After all, even though the chance is miniscule, when that miniscule chance occasion does happen, the result is death -- why not avoid it when all one has to do is to press a button?

Put differently, when: (1) all the preconditions for a rare event is present; (2) the consequence of that rare event will be severely negative; and (3) the amount of effort to be taken to negate some or all of the preconditions is minimal, the rational thing to do is take the steps to negate those preconditions, not to ignore the potential harm based on generalized statistics.Here is an example. Lightning strike is a rare event, but the consequences of a lightning striking on you could be devastating. We all know the preconditions of a lightning strike -- thunderstorm, being near metal, being the highest point of the ground, etc. It is of course silly to worry about a lightning strike on a sunny day. But is it rational to be out on a flat land, holding a tall umbrella with a metal shaft, in the middle of a thunderstorm, because lightning strike is a rare event? Of course not. Lightning strike is real. Once you are hit by a lightning, you will be severely injured or dead. Same with Fan Death. Fan Death is all real. It could possibly kill you. Then why not avoid it, when the steps taken to avoid it is minimal?

Thank you for replying to the comment. Unfortunately the claim you repeated below is still incorrect:

"If there was no fan, the person would develop a layer of cool air around his body through the evaporated sweat, and dehydration would be prevented."

1) No layer of cool air is created by sweating. Sweating cools the SKIN via evaporative cooling, not the air. You even mention yourself that air is a poor conductor of heat and you are exactly right. This is why heat is extracted from the skin vs the air. You are confused because in the winter, the body EMITS heat energy which does indeed create the thin layer you spoke of. Unfortunately, in a hot room, humans do not "emit" cold. In order to get any layer of "cold" you would need a huge temperature differential between the body and the surrounding air (e.g. the body is 5* C and the air is 60*C). In reality, the hottest days on earth are still way too close to normal body temperature to consider anything like this. (This is also why your turbo oven analogy does not apply to humans in a room)

2) What DOES occur in a thin layer around the body (in our summer time example) is a region of high-humidity air. This high-humidity air layer is directly caused by the evaporation that is cooling the body. By using a fan, we can blow this "saturated" air away and bring in "dryer" air that allows faster evaporation and in turn better cooling of the body.

All the confusion may be tied to a misunderstanding of how house fans work. Many people mistakenly believe that fans blow cold air at them, which is not how fans work at all. It is all about humidity and circulating air. The worst part is that you've laid out your argument in a way that would seem logical to people who aren't familiar with the sciences of heat and energy and will inevitably spread these false misconceptions because "it sounds scientific".

I can't stop laughing. The Korean, you had an awesome argument at the beginning, but now, it has fallen apart :(. What's lacking is true-life scenarios that can support an answer.

The answer is short and simple!!! Fan death is association, not causation. Here is my rationale.

Just think back to the heat waves in France a few years ago, a country where most homes are not equipped with a/c, only heaters ( I lived there for a summer). Energy price is insane, another reason to not own an a/c unit. As a result, old people were dying left-and-right because they thought a fan would be enough in keeping them cool. However, we know that fans do not lower the temperature, rather it circulates air, which accelerate sweating as evaporation is being accelerated and old sweat is being replaced with new sweat, cooling the body, which dehydrates you even faster. You're right on that point. However, it is not the causation.

Regardless of a fan, your body is losing so much water, and once it gets below it's functional level, it goes into shock, and you faint or collapse from exhaustion and dehydration. For young people, that's a hard thing to do, as their body is more resilient and easily can detect that it needs more water asap, i.e. you become really thirsty. Even when you're asleep, if it's too hot and you're sweating like crazy, you automatically wake up to get water or to turn on the a/c. However, with seniors and possibly with alcoholics, they're more susceptible to dehydration, as their body has lost the ability to alarm itself to replenish the water it has lost, especially drunks. Hangovers are linked to dehydration, and also, drunks tend to have the ability to lose bodily functions, i.e. them peeing on themselves. lol. As a result of dehydration, the body can go into shock or have organ failures, leading to death if no emergency response is taken, like an iv with fluids and electrolytes.

If you ever ran a marathon and collapsed because of dehydration and became delusional, you realize how deadly dehydration can be.

In addition, many elders lack the mobility or mental capacity to leave their homes. On top of that, you have the grandpas/mas who are stubborn and believe they can handle the heatwave at home without a/c, but with their fan. Sadly, some do not make it through.

It's easy to associate the fan as being the culprit if you arrive on the scene to find it blowing full-blast onto a corpse on the rocking chair. (Spooookyyyyy image!!!)

All in all, it is poor judgment or physical or mental incapacity to leave the house for a place with a/c that proves to be the killer, not a fan, as we all are capable of getting up in the middle of the night to lower or raise the thermostat or to reach for that cold glass of water in the fridge or extra blankets in the closet. Only those who are incapable of doing so are likely to be the victims of fan death. lol. :)

Hi All~!Thanks to many of you for really thinking and researching information before posting. I had seen www.fandeath.net years before, but this post is much more informative!

Let's start with the assumption that the Korean is correct and what we are calling Fan Death is possible. Science is science and in those conditions, seems like people are in trouble.

But what about in non-perfect conditions?

I like the shark attack comparison. I'm sure all Koreans worry about being bitten by a shark, but how many completely stop entering the oceans of the world for the rest of their lives? Or, perhaps more accurately for comparison to Fan Death fear: the oceans, lakes, rivers and pools of the world?

The problem with the Korean belief in Fan Death is their insistence on turning off fans in all kinds of conditions: windows open, warm or cool days, low humidity, etc. How many of us living here have had someone either turn off our fans or made comments about them being on while the perfect conditions for Fan Death were not all (or even none!) present. Many Koreans also have some belief in fresh air which causes them to open windows of homes, buses, cars, offices, etc in spite of the weather. How many taxis have you ridden in (pick any season) that drive with the windows 100% up? Given this seemingly Korean need to have windows open at all times, it’s strange that the number one choice in preventing Fan Death is turning off the fan and NOT opening some windows. By the science, just one open window and Fan Death is no longer a possibility.

In addition, many Koreans seem to believe the fan is capable of making air colder, the same as A/C. (Which, by the way, ruins the reasoning in how it could possibly cause Fan Death.)This belief can experienced by anyone using a fan in the fall, winter, or spring. As an experiment, invite some Korean friends over during any winter month and try hanging out and drying your laundry with a fan. Or observe as fans in Korean homes or restaurants either disappear or get bagged up once the summer is over. The western idea of using ceiling fans in winter to move warm air down is almost unknown here. Why? Because fans MAKE cold air!

Like with shark attacks and life guard warnings of sightings and non-safe times for swimming, wouldn’t it be better for Koreans to know about the perfect conditions (90+F + 70% humidity + dehydration + enclosed space) for Fan Death, yet in non-perfect conditions, enjoy the wonder of a gentle breeze from a fan? Is there an environmental-awareness opportunity here? Could educating Koreans on how often fans are useful and safe then allow them to use them more in summer and winter thereby reducing more expensive heating/cooling methods?

Regardless of the scientific possibility for a fan to be involved in a death of a human, Koreans show great misunderstanding of the basic functioning of fans in their everyday behavior thus underutilizing fans. This will always bother non-Koreans.

Ok I have to step in on the side of The Korean on this one. I happen to LIVE in Daegu and yes it does get hot enough to meet these conditions and it gets that way often. I know many older Koreans who live in small shacks that have little / no ventilation. I also know many of them (especially the older men) enjoy drinking soju during the day and often pass out.

So its perfectly possible for an older Korean man to be drunk on soju during a hot day in Daegu and pass out in his none ventilated one room shack.

And many are correct, the presence of a fan will lower the human's body temperature rather then increase it. But it does this by rapidly evaporating sweat from your body. Thus you sweat more (and become cooler), but use up water at a higher rate. For a young / conscious person this is no biggie, we just drink more water. For an older drunk korean man (or anyone in similar physical condition) who no longer possesses the ability to correct their body's problem, this can be fatal. For once the body's water reserves have run out, the fan just serves to more efficiently heat the body. And a 10 degree increase in core body temperature in a short period of time is entirely possible. In fact I'd call it probable given those conditions. This is basically heat exhaustion leading to heat stroke.

There is no emit heat / cold crap going on. Its simple thermodynamics. Thermal energy will always attempt to equalize. Moving from a higher density to a lower density unless an outside force acts on it (thermal pump). In the winter your body has higher thermal density then the air, so heat is transferred to the air directly around you forming a thermal blanket. In the summer the evaporation effect cause's the air directly around your body to be colder then the air further away. This creates the same barrier. Unfortunately it also slows down further evaporation. So while its more energy-efficient to just sit still when it's hot, its more comfortable to have air being blown across your body (increased evaporation).

Air has a high heat index but a low heat capacity. These qualities make it a great thermal insulator, regardless of direction. Cold things stay cold, hot things stay hot. As long as the barrier of air is not moved it will remain this way.

The death he is referring to is nothing more then heat stroke. Its cause is rapid over heating of the body combined with the inability of the body to control its temperature (due to dehydration).

I didn't read this article but I'm leaving a comment since I'm pretty convinced it could be real as well.

I came across this article because I woke up gasping for air yesterday at 4 am. I actually jumped up on top of my bed from a dead sleep. It was pretty scary and its the first time it has ever happened to me. I am Korean and I was sleeping in a room with a window cracked open with the fan on. The blinds were down so it was pretty close to being closed.

At first I thought it was sleep apnea since I have a problem with snoring. All day at work I was scared that I would experience this again tonight. So, I went online looking for some possible solutions. There wasn't much I could do for sleep apnea except support groups and long term solutions.

Then, about an hour ago, I remembered something my girlfriend mentioned about dying from keeping a fan on. I read a few articles on wikipedia and other sites and am more convinced that it may be due to the fan. Some articles cited that a constant breeze to the face can cause death from dehydration. I am pretty convinced that my snoring combined with the constant stream of air dried out my airways and caused my suffocation. I don't know if I would have necessarily died but I definitely do not want to experience that again. I am placing my comment here in hopes that maybe other people become aware of this "urban legend".

I couldn't agree with the Korean until he said it is a "contributing factor". That is all it is. Under the right conditions the fan can accelerate dehydration, leading to heat stroke. There is no argument there. That is a fact.

The problem is that most Korean people are ignorant to that fact. Most Korean people including my wife and many doctors. "Fan death" is so heavily ingrained in their society that it has become the cause. My wife for example tells me how it makes the air bad by mixing all the carbon dioxide, or some bs like that. She goes on to tell me about the headaches the fan can give her. She is getting headaches only because she knows she will.

The Korean said "the preconditions leading up to Fan Death is identical to what Korean people perceive as dangerous, and also consistent with Korean media report as Fan Death". I find that hard to believe, because we have all heard about the fan sucking up the oxygen, or cutting it up, or causing hypothermia. All of which are just so ridiculous I want to I want to shoot my self.

I sleep with the fan on all year round. It helps me breath in the winter.

hahahahahahahahaha. This blog cracks me up. My friend would easily label the Korean as "intentionally oblivious". It is so great that the Korean has used such well researched data to support such a backwards superstition.

Room temperature would have to exceed 40 degrees celcius to produce any sort of "turbo oven" effect. As long as the temperature in a room (open windows or not) is below that, the fan's circulation of ambient air will in no way raise body temperature (It will actually cool you via the beautiful, alive, method of sweating).

Fan death is retarded, and so is this article's proof, but it was all made in satire (I hope) so I forgive you.

You're lamely trying to support a backwards, ignorant superstition with science, but your theory here is pure speculation.

You're cherry picking ideas and forming hypothesis, but not following them through thoroughly.

I actually wrote about 6 paragraphs here explaining, but I deleted them. It's not worth the effort. You're either being facetious or you're blindly trying to prove a silly superstition from your homeland, or you're just too stupid to understand the concepts involved.

Frankly I don't care which, but as several people have said, it's all too easy to see how a superstition like this could serve a purpose in society (covering shameful deaths), and that's the most likely reason for the myth's prevalence.

The comment by "a" completely blew your theory apart and explained, step by step, why you were wrong. Why did you stop replying to him? You don't want to be wrong, do you? You put a lot of effort into this theory and you're gonna defend it to the bitter end, huh?

1. The Korean stopped replying to "a" because he realized what "a" says, even if taken as true for the sake of argument, does not affect the plausbility of fan death.

2. Gee, the Korean wrote six paragraphs that figured out the universal law of physics, but the dog ate the Korean's keyboard. If you are so cocksure that the Korean is wrong, prove him wrong. And do it without personal attacks, or it will be summarily deleted.

i cant say that i read the entire blog but regarding fan death i will say this. i was in korea for the summer in 1994 and wow was it hot and humid. i remember being inside buildings and the air conditioner was only on for about 2 - 4 hours a day during the afternoon when it was the hottest. made me think about energy consumption. korea has nuclear power so there shouldnt be a problem with lack of electricity. but think about the origins of fan death. when did koreans buy fans en masse (before widespread use of air conditioning)? was there enough electricity being produced back then? i have always thought that fan death may have been an attempt to decrease energy consumption during the brutal summer months in korea. can you imagine at least one fan per household being on all day and all night in a counrty with about 40,000,000 persons or roughly 10,000,000 homes?

The Korean does not know when electric fans were sold in en masse, but Korea did not lack for electricity since late 1960s. If Korean government at that time wanted to reduce electricity usage, they would have just ordered people to do so instead of playing mind games.

Let's say you run a fan in the middle of a hot summer in your enclosed bathroom. Does this mean that not only would you have to worry about "fan death", but that you also have to worry about "shit hitting the fan"?

I must say I am sceptical of the whole fan death thing. I buy the argument that under very specific conditions fans could increase the likelihood of death, but the odds still seem pretty slim. What about the benefits of having fans around, I am sure they save a lot more lives than they cost.

And there is always the correlation causation problem; a lot of people have fans and sooner or later someone is going to die while sleeping in front of a fan.

I don't believe the shark analogy helps your cause. It demonstrates how people greatly exaggerate certain risks. Fan-death is just another great white minding its own business, occasionally in the wrong place at the wrong time.

to restate your argument succinctly: in extreme heat, a fan in an unventilated room can act similarly to a convection oven, thereby raising temperatures just high enough to be dangerous to the weak and elderly.

that's a different understanding of fandeath than is widespread in Korea. this is evidenced by Koreans being more likely to worry about cold fandeath than hot fandeath.

it's further evidenced by the fact most Koreans cannot explain fandeath. isn't it more practical to label it hyper and hypothermia?

next, to take issue with your leap of logic. you do understand the principle of convection heating but you don't supply evidence of a fan heating a room to 61ŸŸ°C.

please link to the experiment you derive your claim from. remember, a turbo oven still has a heating element running at a temperature of 140°C. the heat sources in your explanation are the human body and sunlight.

personally, i admit the slight possibility that, under precise conditions, a fan might cause an attack of hyperthermia in an unconscious and weak individual. but that isn't "fandeath!" it's not even proven possible!

so let's use the freakonomics approach last: 0.006% of the world's population believes in fandeath.

assuming Korea has a per-capita number of medical scientists above the global average and they all believe in fandeath, 0.01% of doctors worldwide support the fandeath theory. doesn't that say something?

to restate your argument succinctly: in extreme heat, a fan in an unventilated room can act similarly to a convection oven, thereby raising temperatures just high enough to be dangerous to the weak and elderly.

Your characterization of the Korean's argument is very correct, and he appreciates that.

that's a different understanding of fandeath than is widespread in Korea.

This part is incorrect. Koreans' understanding of fan death invariably involves heat, enclosed room, and fan directly on the body. Korean people's effort to prevent fan death also involves removing one of the elements - either open a window a little, or have the fan oscillate.

isn't it more practical to label it hyper and hypothermia?

Remember, Koreans did not label anything. It was non-Koreans who coined the term "fan death", and proceeded to mock Koreans based on that term.

you do understand the principle of convection heating but you don't supply evidence of a fan heating a room to 61 °C. please link to the experiment you derive your claim from.

The Korean is working on the experiment to quiet the doubters once and for all -- stay tuned. But at any rate, the convection does not have to raise the room temperature to 61 at any rate, because fatal hyperthermia happens at the core body temperature of 40 degrees.

personally, i admit the slight possibility that, under precise conditions, a fan might cause an attack of hyperthermia in an unconscious and weak individual. but that isn't "fandeath!"

The bottom line is this: the Korean already explained in the post that fan death is a rare event. He also explained that the Korean media often gives a false positive. On top of that, he also explained that most Korean people misunderstand the cause of fan death, and the wrong explanations given by Koreans can be ludicrous. BUT -- like you conceded -- under precise conditions, fan death is real. In addition, those precise conditions are exactly in line with what Koreans know to be the necessary elements for fan death! (i.e. heat, enclosed room, fan directly on the body.) What more could you want from this explanation?

Your argument, essentially, is that the definition of the term "fan death" contains the commonly attributed causal mechanism to the phenomenon (e.g. suffocation, hypothermia.) Because those causal mechanisms are incorrect, the entire definition is incorrect.

That argument is untenable because, as the Korean noted earlier, Koreans did not come up with the term "fan death". Koreans had no say at all about how the term is to be defined. This makes the claim like "what Koreans understand as "fan death" simply doesn't exist" absurd. Technically, Koreans have no understanding of the term "fan death", because it is not a Korean term to begin with.

Instead, Koreans have a very specific understanding of a certain phenomenon - heat + enclosed room + fan directly on the body = chance of death. (For the sake of distinction, let us refer to this understanding as "Fan Hyperthermia".) And the Korean demonstrated in the post that Fan Hyperthermia is completely possible. Again, the Korean readily concedes that many Koreans misunderstands the causal mechanism of Fan Hyperthermia. That may even lead to some Koreans' confusion over what the necessary elements of Fan Hyperthermia would be. Is Fan Hyperthermia the same thing as Fan Death? That's an argument that has nothing to do with Koreans, because Koreans did not come up with the term "Fan Death".

I think you could easily devise an experiment. Build a well-insulated box. Drill a small hole and place a thermometer through along with a rubber cork (or other air-tight non-conductive material).

Deconstruct a fan (any size depending on the size of your box) so that the blades are located within the box but the motor is located outside (to remove your heat source). Again, this would require you to drill a hole in the box and some how insulate the gap around the crankshaft- but without inhibiting the rotation to avoid friction.

I say that you should displace the motor from the box because the size of the average room in Korea (even my friend's 100 square foot apartment) is more than large enough for the heat from a small electric motor to dissipate in, while a small box is not.

Bring the ambient temperature within the box to whatever temperature you believe is a necessary starting point (90 F). Now turn on the fan and monitor any change in temperature.

I bet, based on the first and second laws of thermodynamics as my basis, that the temperature will decrease.

The box, like a room, is NOT a closed system. So entropy WILL increase. This means that trapped energy will necessarily leave the system- i.e. heat will radiate away from the box if its temperature exceeded the surrounding temperature.

Conservation of energy would mandate that the kinetic energy of the motion of air molecules would not ADD heat to the system nor REMOVE heat from the system if it were a closed system.

Because it is not a closed system energy can be added to the system in the form of heat energy, but only if there is an outside source. If you say, put the box under a sunlamp, for example.

Next, reproduce your experiment with a mouse in the box. If the box is of a relative size to the mouse it should adequately replicate the addition of a human into the system.

The mouse might die of suffocation, but only if you make that box air tight, which I HOPE no room people are sleeping in is.

Your experiment gets halfway there, but not all the way. The Korean agrees that your setup -- box, fan, motor outside, etc. -- is exactly right. But the Korean thinks you are measuring for the wrong thing, because you say this: "I bet, based on the first and second laws of thermodynamics as my basis, that the temperature will decrease."

Yes, the Korean agrees that the temperature of the air in the box will decrease. But that's not what we are interested in. The thing has to be measured is the temperature of the body in the room.

Another way of explaining fan death is this: fan death happens because the body temperature rises a lot faster in a hot room with a fan than in a hot room without a fan. Again, compare a regular oven versus a turbo oven. Both can have the same temperature, but turbo oven cooks faster because of the fan.

So the correct experiment is this: prepare the same box you describe, and heat it such that the ambient temperature inside the box is 40C. (Heat stroke can be fatal when the core body temperature reaches 40C.) Put a piece of meat whose core temperature is 37C (= body temperature). Without the fan, measure the time for how long the core temperature of the meat rises to 40C. Take another meat whose core temperature is 37C. Put it in the box with the fan on, and measure the time for its core temperature to rise up to 40C.

The Korean will bet anything that the meat with the fan ON would get warmer faster. In fact, the Korean does not even have to do this experiment, because it has been clearly proven that turbo ovens cook faster than regular ovens -- hence their usage in industrial kitchens everywhere in the world!! Why is this concept so hard to understand?

And for the last fucking time, fan death is not caused by suffocation. As the Korean noted, that explanation is ludicrous.

This part is incorrect. Koreans' understanding of fan death invariably involves heat, enclosed room, and fan directly on the body. Korean people's effort to prevent fan death also involves removing one of the elements - either open a window a little, or have the fan oscillate.

we'll agree to disagree on this. i've lived in Korea for 27 months and have discussed fandeath with many Koreans. none ever explained it as you have nor have they expressed the concerns that would follow from your own understanding of fandeath.

From The Korean Herald:The heat wave which has encompassed Korea for about a week, has generated various heat-related accidents and deaths. At least 10 people died from the effects of electric fans which can remove oxygen from the air and lower body temperatures...

On Friday in eastern Seoul, a 16-year-old girl died from suffocation after she fell asleep in her room with an electric fan in motion. The death toll from fan-related incidents reached 10 during the past week. Medical experts say that this type of death occurs when one is exposed to electric fan breezes for long hours in a sealed area. "Excessive exposure to such a condition lowers one's temperature and hampers blood circulation. And it eventually leads to the paralysis of heart and lungs," says a medical expert.

this is one example. if you want more i can provide them.

Remember, Koreans did not label anything. It was non-Koreans who coined the term "fan death", and proceeded to mock Koreans based on that term.

you're right, Koreans have no term for this urban legend that foreigners call "fandeath."

if you want me to concede that, under the precise conditions we've agreed to, a fan can possibly increase chances of hyperthermia, i do. i'd like to see a scientific experiment testing this idea.

but i say again that is not the fandeath that Koreans understand and are "mocked" over. the average Korean believes something far more ridiculous!

even if all Koreans were as level-headed as you, isn't it more practical to reframe this issue and educate about the dangers of hyperthermia?

this entire concept is akin to blaming the water bottle when someone chokes and drowns while drinking from one.

lastly, i don't think i need to explain the faulty logic of the following argument:Then why would the EPA give a warning about it?

we'll agree to disagree on this. i've lived in Korea for 27 months and have discussed fandeath with many Koreans. none ever explained it as you have nor have they expressed the concerns that would follow from your own understanding of fandeath.

Sure, let's do that. But since you described your qualifications, the Korean will describe his: he lived in Korea for 16 years and 8 months, and has visited Korea every year since. Every summer (especially as a child,) he was lectured about the danger of electric fans from his parents, relatives, neighbors and teachers. And their stories never once changed -- they always involve heat, enclosed room and fan directly on the body.

Then again, misunderstanding is always possible, and it could have just happened that you spoke to a disproportionate number of people who misunderstood the elements. Or there could have been a language barrier. Who knows -- if that's your experience, the Korean can't contradict it. It probably wise to agree to disagree.

2.

Korea Herald article really means nothing, because the Korean already said in the post that media often has lazy coverage and has numerous false positives. And trust me -- Korea Herald and Korea Times are the laziest of them all. (This coming from personally knowing a lot of Korea Herald reporters.) The Korean sincerely doubts that the reporter for the article even interviewed a "medical expert" quoted.

3.

but i say again that is not the fandeath that Koreans understand and are "mocked" over.

Again, if Koreans do not even have the term "fan death", how can you say what they do and do not understand by that term?

4.

this entire concept is akin to blaming the water bottle when someone chokes and drowns while drinking from one.

They are not akin at all. Drinking from a water bottle compared to, say, drinking from a cup, does not elevate the risk of choking. On the other hand, being in a hot, enclosed room with a fan definitely elevates the risk of hyperthermia compared to being in a hot, enclosed room without a fan. In such case, it is perfectly normal to be cautious of the fan. In fact, it would be unreasonable not to.

5.

isn't it more practical to reframe this issue and educate about the dangers of hyperthermia?

Why do you assume Koreans are not doing that? Take a look at this article: Link. Linked article is talking about how Korea Meteorological Administration invited Dr. Kalkstein (referenced in the post) to speak about the dangers of hyperthermia at Seoul Plaza Hotel, and specifically the dangers of using a fan in an enclosed room. The article states that Dr. Kalkstein is also working with the Korean government to develop Extreme Heat Event Alert. (A fan death alert!)

I too feel that maintaining the fan/heat/room (what has been termed "Fan Death") explanation is simply bad science.Such deaths must be explained by way of scientifically-proven and known causes. If a person diesfrom hyperthermia, we need to label it thusly; not to would be doing a great disservice to others at risk. We can't tell our grandparents to avoid such heat-related deaths by simply turning the fan off--we need to buy them a good air-con and help them pay for the electric. We need to blame the true culprit in such deaths:hyperthermia, over-consumption of alcohol, sleep disorders, etc.To simply blame it on an innocent fan helps nobody; further deaths are not effectively prevented.

Good explanation, but you need actual scientific proof from experimentation under controlled conditions.

Finally, I think you may be doing a disservice to Koreans by saying that most believe in this phenomenon--embracing it is a matter of national pride. My family and friends don't believe in this; in fact, they call it "superstition." I do think many people are misinformed on the subject; but it may be a bit pointless to try and prove such silliness is "real" other than to help people save face for believing in this.Might you have a similar explanation for cholera leg cramps actually being caused by rats crawling up your legs under the skin? Might this explanation help more Koreans save face for believing in something silly? (Rubbing the cat skin on your legs scientifically takes away the pain the rats cause?)Is this science or face-saving for a national cause?

Turbo ovens can cook the same amount of food at the cooking temperature that is about 50 degree Fahrenheit (30 degree Celsius) lower than a conventional oven. [...] This means that although the room’s air temperature is 90 degree Fahrenheit, with a fan on, your body is cooking at the same rate as being in a room with 140 degree Fahrenheit (61 degree Celsius).

You tried so hard to make a well-founded scientific argument, but you presented a linear correlation between gains in efficiency cooking with a convection oven at (which is done at high heat) and using an electric fan (which is typically 3-4 times cooler than an oven).

It is absurd to think that because circulating air allows cooking to happen at temperatures up to 50 degrees lower in an oven that the fan is responsible for this 50 degree difference and by extension compounds heat at room temperature. To place your example in a different context, wouldn't you laugh if I suggested that it would feel like a comfortable 75 degrees in your refrigerator if only you had an electric fan with you?

It is also likely those publications you used as example warn about using a fan in closed rooms whose temperatures exceed 90 degrees because 90 is an easy to remember number, close to, but not above a body's typical core temperature; thus is appropriate for a broad non-scientific audience.

In reality the fan only circulates air and acts as a catalyst by speeding up the rate at which heat (or cold) affects something. In other words, a fan may accelerate the rate at which a body experiences overheating, but a fan cannot cause these conditions to exist.

Fan death may very well be the Korean equivalent of an old wives' tale. Many of us subscribe to poorly founded beliefs that better our lives, but as an American I don't try to defend "an apple a day."

I hope I've been able to dismantle the majority of your argument and supporting material so that you'll consider revising or removing your post. My wife is half-Korean and it's embarrassing how vehemently and poorly fan death is defended.

It is absurd to think that because circulating air allows cooking to happen at temperatures up to 50 degrees lower in an oven that the fan is responsible for this 50 degree difference...

The only difference between a regular oven and a turbo oven is that a turbo oven has a fan. And a turbo oven cooks at up to 50 degrees lower temperature than a regular oven. How is the fan not responsible for this difference?

...and by extension compounds heat at room temperature.

That's not true; a fan does not add heat to the room. Nor is it the Korean's argument. Please read the post again carefully.

In reality the fan only circulates air and acts as a catalyst by speeding up the rate at which heat (or cold) affects something. In other words, a fan may accelerate the rate at which a body experiences overheating...

"Catalyst" is not the right term (because it implies something chemical,) but you are 100 percent correct that a fan accelerates the rate at which a body experiences overheating. That's exactly the danger of a fan in a hot room. The acceleration can be the difference between life and death, especially given that the atmosphere of the room will slowly cool.

... but a fan cannot cause these conditions to exist.

Again, agreed 100 percent. And the Korean never said that a fan can cause a higher temperature. The Korean's point is that with a fan, your body will experience heat stroke as if you are sitting in a room with higher temperature.

It seems that the current consensus of the blog is that a fan might accelerate the rate at which a person loses water through perspiration, which will eventually lead to dehydration, followed by death due to hyperthermia.

It seems to me that there is also a fundamental flaw in this argument. We have to remember that the body is not some machine that sweats at a constant rate. The only circumstance under which the fan might increase the rate of perspiration is if the rate of heat loss without the fan was too small to maintain a healthy body temperature. In that case, if there was no fan, you would become hyperthermic anyway. Thus, it seems that the fan is probably decreasing the likelihood of hyperthermia, not increasing it. Consider the following example: You run a marathon and then can't sweat because of some chemical that you've ingested. Clearly, you are going to get heat stroke faster than someone who could sweat, even though they will lose water at a faster rate.

Thus, the fan might cause dehydration, but I find it very unlikely that the fan would lead to hyperthermia in cases where hyperthermia would not occur without the fan. It seems that the fan might therefore contribute to death through some other effects of dehydration, but then again, the positive effects of the fan might very well outweigh the negative effects. Who knows how many instances of heat death could have been prevented in Korea if well-hydrated individuals had left their fans on, helping their bodies cool off, instead of shutting off their fans because of a scientifically unproven belief?

This whole argument is ridiculous on both sides - who cares if there's a slight scientific chance that fan death might be real or not. There's a slight scientific chance that the lochness monster might be real too...the underlying argument here has nothing to do with science. The reason foreigners in Korea bemoan fan death so much is because it is the least likely idea representing what might be labeled as 'a stubborn culture.' Even if fan death is possible it is not probable, so the warnings about it far exceed the dangers. Foreigners only take Koreans to task about it because Koreans are so adamant in defending it and Koreans defend the idea because (in general) they are so furiously nationalistic (which is understandable given their history of oppression.)I think everybody in this argument needs to step back and ask why they are making such a big deal over it...is it because of the dangers of fan death? Really? Or is it a more serious commentary on cultural differences? If it is the latter then you need to ask yourself if you are being racist or not.

When I first heard about fan death, I always wondered where people find a completely sealed airtight room anyway. A bank vault? Sure enough, you'll die of suffocation if you stay locked in one for too long but not because of fans.

I'm not sure about this whole convection oven argument - how high must the temperature be, how long do you have to be in the room, and how weak do you have to be before convection becomes a significant factor? However, even if it's valid, it seems to me the most salient advice you could give people isn't 'Beware of the fan!' but 'Open a damn window!'!

Before I completely take back all the laughing I've done at fan death, all the explanations apart from The Korean's (CO2, hypothermia, bad air) don't make any sense. Now for the taking back some of the laughing I've done:

http://www.csgnetwork.com/windchillcalc.html

Plug in 90 F or higher and crank the wind speed up to between 3-8 mph (average box fan wind speed) and you'll get significantly higher temperatures.

Keeping other factors negligible, (windows shut, no AC) should the increased heat imparted by this convection effect (not 61 C but still a few degrees) surpass the increased heat lost via evaporation from reduced vapor pressure from the wind, the fan will be hurting more than helping. If you are overheated, drunk, and dehydrated, you will become more overheated, maybe drunker, and more dehydrated faster in these conditions.

You don't need to set up an experiment, just take the already agreed upon formulas for convection, vapor pressure, and the physiological stuff and make a chart or something to tell people when its OK to turn on their fan (most of the time).

Thanks for a very interesting post. I definitely agree about the dangers of "carelessly reported cases of fan death". I had thought fan death was bogus for years because I actually knew a foreigner living here in Korea who officially died of fan death. Reality was that he had accidentally overdosed on valium and booze,left the air con running all night and his heart had stopped. After that I sort of got the notion that fan death might be a convenient explanation for certain embarrassing causes of death in Korea. I really have no idea how true that might be though.

The applicability of fans to dehydrationYou make the argument that because fans accelerate the evaporation of sweat, people will sweat more. This is incorrect.

First, some assumptions. The person sweats normally--this means if their body temperature is above normal, they sweat, and if it's normal or below, they do not. The relative humidity is less than 100%.

As a person's body temp rises, they sweat. As the sweat evaporates, it cools the skin. Once the body temperature is no longer elevated, sweating ceases. This happens regardless of the rate of evaporation.

Additionally, every unit of water that evaporates cools by the same about of energy. Therefore, if your body generates 100 calories of heat due to metabolic processes over some time, a specific amount of sweat will remove that heat, regardless of whether is is over the course of a minute or an hour. So the only way that you will lose more water to evaporation is if you're going to overheat without the fan.

Let's think of a body sweating like turning on the air conditioner. An air conditioner always uses the same amount of energy to run, and it always removes the same about of heat whenever it's running. You could run the air conditioner for the first 12 hours of the day, cool your house to 40F, then turn it off the the next 12 hours and let it heat back up to 80F. Alternatively, you could have it cycle on and off over the course of the day, running a total of 12 hours in short, 15 minute increments. This would keep the temperature in your house a more consistent ~60F. But the AC would be on for 12 hours in each case, so you would require the same total amount of electricity.

Now suppose you have a much smaller, but equally efficient air conditioner. To keep the house at 60F, it has to be on the whole time. So it runs for 24 hours a day. It also uses the same amount of energy as the bigger AC unit that runs only 12 hours a day.

In this case, you don't care which AC unit you have. They both keep the house at 60F and use the same amount of energy. But suppose that 60F is not comfortable--instead, you want 50F. In the case of the big AC, you can just let it run longer, and cool the house to 50F. It is possible that you don't have enough electricity to do so, but it is at least a possibility. But in the case of the small AC, there's no way to cool the house to 50F--you're already running it 24/7! Even if you could buy more electricity, you'd still overheat!

This is the same with sweat. A fan allows sweat to evaporate faster, allowing it to remove more heat in a given time, just like the big AC. Yes, this costs additional sweat (electricity), but you can do it. Additionally, because you can stop sweating (turn the AC off), you don't HAVE to use all of your sweat just because you can. So the only case you get dehydrated FASTER because of the fan is in the case where you would overheat without the fan.

Now, to tackle some of your counter-arguments that you gave in the comments:"The Korean's point is that with a fan, your body will experience heat stroke as if you are sitting in a room with higher temperature."

This is only true if the temperature of the room is higher than body temperature. No exceptions. Heat always moves from hot to cold.

"Heat index of 99F can occur when the air temperature being 90F and humidity at 60 percent. This is easily achievable during summer in Korea."

While temperature and humidity are inputs for determining the heat index, "like the wind chill index, the heat index contains assumptions about the human body mass and height, clothing, amount of physical activity, thickness of blood, sunlight and ultraviolet radiation exposure, and the wind speed." (Ref: wikipedia). So please don't assume that the heat index can be directly related to the ability to maintain homeostasis.

I know I'm like a year late replying to this post, but I just recently found this blog through a friend of mine.

I have first hand experience with all of the science provided by The Korean in this post. I live in Bakersfield California; the hottest town in the pacific south-west. We have fluctuating humid and dry weather throughout summer, but the temperature is always the same: averaging 105f may-august. On top of that, we have a green house inside of a green house effect here because Bakersfield is over 2,000 miles below sea level and surrounded by mountains, which acts as a crater where a thick layer of smog settles from not only my sprawling metropolis, but also every surrounding city from San Fransisco to San Diego, over the city tapping our heat, and generating more by the minute. We are the necropolis with the worst air quality in the world. Every year the heat wave causes a ridiculous number of deaths in my city. In fact, the temperature has increased by over 15 degrees in my life time, and continues to rise. Most experts agree that it's because of the recent population boom increasing he amount of smog created, thus increasing he heat. See again green house inside of a green house.

Back in 2002 I had to move into a house that was built in the early 1970's that only came with a swamp cooler in the living room. The layout of the house is a rectangle where the rooms are connected by door ways and no hallways. Imagine a rectangle with just 4 rooms and no hallway basically. My bedroom is the last room where the swamp cooler never reached(in fact, the swamp cooler was only effective in the room where it was in-the living room, and staying in any of the other rooms where circulation didn't exist except windows was impossible for longer than like 3 minutes. And the kitchen? Trying to cook was impossible, so we knew our pizza delivery woman very well) and the windows face the sun set. So my room is essentially a broiler. One day, I actually tested the heat in my room just after night fall, when the room was at it's hottest, and the thermometer read over 120f. In order to keep my room cool during the 12 hours of unGodly heat I had to suffer through during the hours of sunlight shinning onto my windows, turning my bedroom into a pressure cooker, I had to use portable fans. Two of them, blowing in opposing directions, but both aiming at me. But only that created a whole new set of problems: suffocation.

I would have to drink three times as much water as my body sweated out per hour in order to not suffocate during the three season of summer we have here.

During the day it was ok as long as I had dark enough curtains to keep most of the light out, which in turn kept most of the heat out, and drank plenty of water. At night however, I had to open the all of the windows in my room at least 6 inches each to circulate the air, otherwise I would have died after just one night. Not joking. I had a few near misses over the 6 years I spent in this house without the AC unit I have now. I was hospitalized 3 times from dehydration because of the fan/heat/humidity co-co-combo breaker. Some nights, because of extreme heat waves, even leaving the windows open wasn't enough. The fans I had at the time didn't oscillate. So, no breeze+fan+heat+humidity = a trip the hospital. Yep.

Fan death is not only real, but in SoCal is happens every summer in the hundreds. The news just doesn't report them as portable fan-pressure cooker deaths. They're attributed to the heat/humidity and that's about it, but the reality is that fans do play a critical role because 8 out of 10 in-home heat strokes took place in homes without AC units and portable fans were present. Usually in the room were the bodies were discovered. Don't believe me? Do the research yourselves.

While your situation sounds like it really sucked, you've got a few problems attributing it to the effect of the fan.

1) The temperature was 120F, well above body temperature. Fan Death (and the Korean's explanation of it) supposedly operates at temperatures below body temperature. That makes a very big difference when considering whether an environment is going to make something heat up faster.

2) You say you drank 3x the amount of water that you produced in sweat, and that this somehow indicates that the fan is dehydrating you. If the fan were dehydrating you, you would be sweating MORE than you drank, not the other way around.

3) You never mentioned what happened if you didn't have the fan on. How can you say that the fan contributed to the problem? It is just as likely to have been the open windows as the culprit.

4) If you're trying to prove the existence of a phenomenon that is not readily accepted, the responsibility is YOURS to do the research.

This is not meant to imply that your did not experience perilous dehydration, only that attributing it to the effect of the fan is not a logical conclusion.

@P.Dishy Wow. What the fuck is your problem kid? If you are this serious about proving "fan death" wrong then do the science yourself and I really hope you die trying. Instead of offering some explanation yourself, or proof, a first hand experience you go on a fucking rampage and attack innocent people with your lame attempt to prove some jerk on the internet wrong. Get a fucking life. Or at the very least some common sense and a news paper.

It appears that your most important point is that a fan does not make one sweat faster. But that does not disprove fan death.

Suppose, for the sake of example, that a person is sleeping on the floor of a very hot room (as many Koreans sleep on the floor.) But as we know, heat rises. So in fact, the floor will be a little cooler while the ceiling will be a little hotter. So the person sweats less lying down on the floor compared to, say, being suspended from the ceiling.

The presence of a fan changes things -- and in fact, this is exactly how turbo ovens work. Fan forces air circulation, which makes the entire room temperature uniform -- and makes the floor temperature higher than it otherwise would be. And this difference is significant (particularly in an enclosed room,) as exemplified by the increased efficiency of a turbo oven.

Another thing you overlook is that we are not dealing with a hunk of meat in a temperature-constant, but a person who is sleeping in a room whose temperature is affected by the outside weather. Essentially, your point is that the same amount of sweat lowers the body temperature by the same amount, and the fan only changes the time it takes to lower the body temperature. But the question of whether it takes 4 hours to fully dehydrate or 6 hours to fully dehydrate makes a big difference. The temperature might cool down enough to prevent heat stroke in 6 hours, but not in 4. The person might wake up in 6 hours, but not in 4.

As to your other point that heat only moves from hot to cold -- again, we are dealing not with a hunk of meat, but a human who generates heat internally. If a human loses the ability to sweat (through dehydration) and can no longer cool herself, hyperthermia will happen even in ambient temperature that is lower than the body temperature required for heat stroke. The ambient temperature only has to be not low enough to completely negate the effect of the human's internal heat generation.

Korean, I'll email you with my full response. It'll definitely get clipped by blogger. In the mean time, here's an important part if it:I think there’s a slight nuance that you’re missing. You interpret my point as “the same amount of sweat lowers the body temperature by the same amount.” What I actually mean is that the same about of sweat removes the same about of heat. Heat and temperature are not the same (that’s why I tried to use the A/C example).

Let me try another way of explaining it. Let’s say a person, who weights 50kg, has the capacity to sweat one liter before being completely dehydrated. And let’s say that the room is at body temperature, 98F, so that the only way heat is removed is by the evaporation of sweat. We’ll also say that the body is producing about 60 kilocalories of heat per hour. Finally, we’ll say that one liter of sweat can remove 240 kilocalories of heat. We know that a fan will cause sweat to evaporate faster. So we’ll say with a fan sweat will evaporate at 250mL per hour, and without a fan, it’ll evaporate at 167mL per hour.

So let’s put this person in a room without a fan and see what happens. During each of the first six hours, the person creates 60 kilocalories of heat. Without sweating, this would increase the body temperature by about 1.2C each hour (one kcal raises 1kg of water by 1deg C). But the body can sweat, so it sweats and the maximum amount of sweat evaporates (167mL). This amount of sweat can remove (.167 * 240) = 40kcal. So even sweating the maximum amount, the body accumulates 20kcal of heat per hour. At the end of six hours, when all the sweat is gone, the person’s temperature has risen by 2.4C.

Now let’s put them in a room with a fan instead. The person still produces 60kcal of heat. During the first four hours, the person sweats at a rate of 250mL per hour. This removes (.25 * 240) = 60 kcal each hour. So at the end of the first four hours, the person has accumulated no heat, his temperature remains 98F, but he can no longer sweat. Over the next two hours, he continues to produce 60kcal per hour, but since he’s out of sweat, this heat accumulates in his body, raising his temperature. At the end of these two hours, he’s accumulated 120kcal, which increases his temperature by 2.4C.

So what’s the point? The point is that the same amount of sweat removes the same amount of heat, so if someone runs out of sweat, they can be no worse off than if the environment limited the rate of their sweating. You’ll notice that in our example, in the case without the fan, the person starts overheating immediately (after even the first hour, their temp has risen by 0.4C). But in the case with the fan, the person stays at normal body temperature all the way until he runs out of sweat. And after he runs out, his body temperature is never higher that the no-fan case (at 7 hours, they’re both 3.6C too hot, for example).

Let me reiterate that point: at no point is the person with the fan hotter than the person without the fan.

You point out that the slower-sweating person might be “saved” by falling temperatures. Even though the person overheats somewhat, because they don’t become totally dehydrated, they survive. This would only be true if fan death were caused by dehydration. You argue that it is due to hyperthermia.

Dear Korean,Iwas just wondering if I could translate this into Romanian and post it on my blog. I enjoyed the article and I'd like to share it with the not-so-lucky non-English-speaking people in my country.Oana

I think anything that has an effect on temperature can kill vulnerable people, but fan death is not going to be the biggest cause. Hundreds of people die related to heat stroke in America every year, and a lot of them probably had fans running, but it probably wasn’t the fans, it was the heat, the dehydration, and their weak physical condition.

Pointing to electric fans as the cause in the absence of clinical trials is a rather poor way of releasing health information, especially when even in the Korean media the number of people who purportedly die from fan death is less than a dozen a year. Was it fans? Or was it the heat? On the whole, wouldn't most people agree fans help more than they hurt? Changing your entire behavior on one very exceptional case is kind of like trying to prove other urban myths correctly based on a small technicality.

What other good advice based on facts can you give people that would have nothing to do with fans in the conditions (hot, no circulation) he specified: drink plenty of water, keep cool, and keep the room ventilation circulating by opening windows and doors.

What I’m saying is that this myth is the truest example of a cultural red herring, a mythological trend exacerbated by human stubbornness. Every culture has it. I doubt that the Koreans would persist in this if other people weren't ridiculing it.

For example, many affluent Americans believe that vaccines causes diseases like Autism. Many Americans believe Obama was not born on US territory, and that he is Muslim. Many Americans believe in Aliens, and many Americans don't agree with Global warming, and/or evolution.

I found his article extremely entertaining, but that doesn't mean he’s credible or neutral in this piece. His job is to write an entertaining piece, and I was very impressed with his wit and prose.

I think you guys are getting hung up on the sweating/dehydration question. Isn't the salient point that the effective temperature in the fan room is always higher because of the windchill effect?

I think where the Korean got confused was ceding the point about how convection ovens work. It's NOT just that the circulate heat more evenly. The moving air also eliminates the thin layer of thermal insulation around the food, so it cooks faster at a lower oven temp.

Dear Korean,You research and explanations were very impressive. However, "Fan death is real" is a misleading statement. Your statement should read "Fan death is possible in a very small, but negligible percent of cases and it has not yet been proven scientifically" Something like that. Gomushin Girl hits the nail right on the head with the EPA Reference and the idea that the coroner might be using fan death as a cover to time on the job or "save face" for family members of a victim that died of drinking too that night or a liver failure, or other embarrassing health condition. I have been living in Bundang, South Korea teaching for about 15 months now. I have to disagree with you a little that by and large (since I have to generalize here) Koreans have the same critical thinking skills as some other Western Societies. I feel the jury is still out on that one. If you look at the structure of Naver's web portal search model vs Google's Algorithem based model. Naver's search model focuses on what is popular (has the most hits that day) and places. That idea is very telling for a society and the way it thinks. I have witnessed the same pattern in relation to brand name preferences by some Korean friends of mine. People prefer brand name products and think their quality is better because they cost more. There is no analysis of the type of product or brand comparison of a cheaper competitor. The same phenomena exists with the Hagwons (institutions). The most expensive hagwon has to be the best because so many people say it is and they want to go there. When in actuality a slightly cheaper hagwon might provide a better value, but often no critical comparison is made b/c the group has already given the "answer." I could go on and on... To say this type of herd consumerism doesn't happen elsewhere is ludicrous. However, I think it maybe more pronounced in South Korea due the history and societal/cultural structure. I think that Korean Society follows a more group think or herd mentality than other Western Societies which tend to put more emphasis on individuality and individual rights. Thus, individual thinking and decision making is born and nurtured. Korean Culture puts more emphasis on the family (a group). In regards to thinking critically on one's own and wanting to stand out from the crowd as an individual it seems less practiced by some Koreans. So, I do think there is some truth to the idea that Korean Students (students that were educated in South Korea) at least don't think critically as often as other non-Korean Students. However, I could be wrong and not have enough exposure to more of Korean Society.

Thank you for you analysis and thought. I look forward to reading more of your blog in the future :)

The idea of the thermal insulation layer around an item is simply not true. No matter how thick or thin you posit this layer to be, air molecules don't have the same viscosity that water does. Gas molecules are in constant movement, and there is a constant exchange of the more energetic (hotter) molecules with the less. To the extent that there is a cooler zone around a cooler body, and there is, it is maintained by a constant flux of heat into the body. No static protective layer is or can be created.F'real. Fan death is not real. It's a name for death by unknown cause. It's also not evidence of lack of critical thinking skill, but rather presence thereof. The human mind tries to explain things it can't. This is just an odd manifestation of that in Korea. I think you could argue equally well that religion is an example of a lack of critical thinking. Not really, just an attempt to explain the unexplained. The key factor is the last part of your article. A lot of people DO know it's a superstition. Those who don't don't because it's just not that big a deal. Plenty of people in my country think that breaking a mirror is bad luck.

Snap, you're right. Sorry. On re-reading, that sounds tardesque. I would stick by the idea that that layer is very limited in its temperature control characteristics, unless it's protected from free exchange by something like a sheet or clothes.

A better objection, in this case: the layer around the body would be HOTTER than the surrounding air. The reason sweating cools down the body is because it requires heat for water to vaporize. Some of that heat comes from the body. Once the water is vaporized, it enters the air, adding that thermal energy. The resulting vapor doesn't cool down the air any more than the air in a sauna is cooled by the steam.

I replied to a link to your article on another forum, but I'm too lazy to edit it so I'll just post my rebuttal below.

The blogger says that the reason you die is that your body overheats because the fan takes away the cover of cool air caused by sweat around your body on a sultry day, causing you to die of dehydration or to heat up when your body runs out of sweat. But that's just an example of begging the question--I was taught that when you perspire heat is taken up to the top of your skin where it warms up the sweat on your skin, and when a passing breeze touches that sweat, it carries the heat (and possibly some sweat) away from your body. The whole point of perspiring is to take heat from your body, which can be aided by a passing breeze. The author doesn't seem to understand what's going on, because that layer of cool air around your body that he's talking about doesn't actually exist. You just feel cool because the hot air is leaving your body on the wind. (More accurately, water molecules are evaporating off of your skin, taking away the heat.) But there is no cool air around your body that is magically brought about by your sweat...rather if anything there is an especially hot layer of air around your body that is carried away from you, leaving you to feel cool.

Now I understand that if the circumstances were right, say 100 percent humidity, the air wouldn't take away your sweat. But isn't 100 percent rain? Like magic clouds forming in your HOUSE?! Even at a stifling 95% humidity, some water would still be able to evaporate off your skin. (In fact that is the reason it feels hotter when its more humid is that water cannot evaporate off your skin because the air is so saturated with water, that the air can't hold much more.) In extreme humidity , your sweat would be dripping off of your body, carrying your heat with it...only now it would drip onto the floor instead of evaporating into the air, where the heat would dissipate into your floor and hopefully leave your house through the ground. What an icky situation, but the fan would still help by at least blowing your sweat away.

If the temperatures were somehow so hot that your body couldn't produce sweat fast enough to keep up with the fan, you would have died of a heatstroke anyway regardless of whether the fan was on or not. Now as for dying because the fan took away all of your bodily fluids, well that's just because you weren't drinking enough...don't blame it on the fan. You're supposed to drink at least 2 liters of cups a day (if memory serves me right), more if its hot. Do you really think you're going to sweat 2 liters while you sleep without waking up? That's like peeing twice through your pores...its an impossible rate...I mean unless in this closed room, you've got a Hollywood or Boeing jet-fan blowing your hair back at some ridicolous speed!

(Need I mention that a closed room that releases no energy is impossible too? Due to convection your heat should be permenating to some degree through the walls...concrete floors included. Assuredly it would be better to open the window though, but the reason opening the window works is because it lets the heat move and escape. Letting heat move is a GOOD thing...and damn his convection oven theory. Although I appreciate the time he takes maintaining that large and interesting blog, but that author really has no idea how convection or perspiration work....)

So if the fan is cooling you down by circulating the air, at the expense of making you sweat, it just seems to me like the preventative solution is to just to drink more water and stay cool by keeping the fan on. Oh and use a hankercheif to carry away more of the heat with your sweat.

It would seem that your article is quite polarizing even after nearing 2 years since it was originally posted! Unfortunately, I, too, disagree with what you have written, but I feel that a different approach is necessary to explain why. (Keep in mind that I in no way intend this comment to be an attack on Korean beliefs or the Korean culture. I think general consensus here is that every culture and everybody is susceptible to believing strange/unproven things, including me!)

I feel that what we have here is a classic case of confirmation bias. That is to say, you have come to a conclusion before you have done research/testing. In this case, you have an emotional investment in fan death being a real phenomenon and have set out to prove it. The part of your article where you suggest that Wikipedia is "dripping with contempt" says to me that the world community's view of not believing fan death makes you feel rejected. Oddly enough, there is a very informative article about confirmation bias on Wikipedia which I suggest you read - even though I will admit right now that Wikipedia is not always the most reliable source! Further proof of your bias is in your article's title: "FAN DEATH IS REAL". A neutral party would have said something more along the lines of: "An Investigation of Fan Death".

The one thing that has prompted me to write a comment, however, was your quote "Here is the science of how a fan could kill". Proving that something "could" happen is simply fishing for answers via confirmation bias. Real science is not done through speculation, finding facts in texts, or using mental gymnastics to prove a point. Instead, real science is done through direct observation. Scientifically speaking, either things happen or they don't. If you were to really prove, scientifically, that fan death were a real phenomenon, you would have to have an autopsy done on a dead person whom you speculate to have died from fan death, then exhaust all other reasonable medical possibilities, then have the results replicated by another, non-bias party. Outside of untrustworthy media sources, this evidence does not yet exist.

Compare this idea to shark bites, something which was discussed earlier in the comment thread. You can prove that people have been bitten by sharks and that, even though it is a small risk, shark bites are a real danger. We can see people who have sustained injury from shark bites and have substantial evidence for that. We have not witnessed anybody die from fan death, nor do we have any sort of physical evidence of it yet. Therefore, your explanation is speculation at best - it is far from scientific proof that fan death exists. Until you can prove beyond a reasonable doubt in this manner that fan death is real - with proof - nobody has any reason to entertain the possibility of its existence. In this case, the burden of proof would lie on you, as people like me who do not believe in fan death cannot prove a negative. That is to say, we cannot prove that fan death "doesn't" exist in the same sense that we cannot prove that yetis "don't" exist.

Compare this idea to shark bites, something which was discussed earlier in the comment thread. You can prove that people have been bitten by sharks and that, even though it is a small risk, shark bites are a real danger. We can see people who have sustained injury from shark bites and have substantial evidence for that. We have not witnessed anybody die from fan death, nor do we have any sort of physical evidence of it yet. Therefore, your explanation is speculation at best - it is far from scientific proof that fan death exists. Until you can prove beyond a reasonable doubt in this manner that fan death is real - with proof - nobody has any reason to entertain the possibility of its existence. In this case, the burden of proof would lie on you, as people like me who do not believe in fan death cannot prove a negative. That is to say, we cannot prove that fan death "doesn't" exist in the same sense that we cannot prove that yetis "don't" exist.

To put it in different words, you have to realize that “proving” something COULD happen proves nothing. Science already operates under the principle that anything CAN happen, and is, thus, willing to accept any possibility in light of real evidence. For example, let’s say if I tried to prove that reindeers can fly. I can look through all kinds of texts and brush up on my knowledge of scientific concepts to find out that maybe, under some strange circumstances, reindeers can create an electromagnetic field under their hooves to hover above the air and technically “fly”. This point, however, would be moot: it does not in anyway prove that reindeers fly. On the other hand, if somebody observed a reindeer flying, science would have no choice but to accept reindeer flight as real, regardless of if I argued that reindeers could fly before the fact. In this same sense, your entire article is a moot point, as anybody would have accepted fan death as real already if somebody has substantial physical evidence proving it. As stated earlier, this evidence does not yet exist, so we have no reason to entertain the existence of fan death until this evidence is presented.

Unfortunately, judging from your previous responses, I feel that no argument will sway you, the true believer, from your beliefs. With that being said, I encourage you to propose your argument to a scientific research institution if you feel this strongly about it. It would truly be a scientific breakthrough if you could prove that electric fans could kill! (And I use the word "prove" in the most rigorous sense here) I will leave you with a quote by Michael Shermer, founder of the Skeptics Society, which I in no way intend to be derogatory:

"Smart people believe weird things because they are skilled at defending beliefs they arrived at for non-smart reasons."

Again, we are dealing with a human, not an automaton with a sweating mechanism. The fact that you are only considering thermodynamics without considering biology is the reason why you can't get your head around fan death. Sweating is not a direct function correlating to the temperature. Some people sweat more at the same temperature, and some less. Especially children and the elderly have a relatively difficult time maintaining body temperature. The same with the intoxicated.

If your theory is correct, then it must be impossible to die from heat stroke when the temperature is lower than 98.7 F, because there is no way the body heat can elevate to around 104 F, where heat stroke occurs. As you put it, the only way you could die from in that condition is dehydration (i.e. running out of water through sweat,) not hyperthermia.

This is obviously untrue. In fact, the EPA flier cited in the post makes it clear. (At p. 13.) Among American cities, the no. 2 and no. 3 in heat-related mortality rate are Providence RI and Hartford CT, respectively. Providence's July temperature average at around 82.5 F, and Hartford at 73.7 F. The highest temperature EVER at both Providence and Hartford was 102 F. (In contrast, Phoenix AZ, an extremely hot city, is near the bottom.)

It is beyond the Korean's expertise to exactly explain how much sweat comes out in response to ambient temperature. What the Korean does know is this: Fan death is a form of hyperthermia, and hyperthermia can occur at ambient temperature lower than body temperature. In fact, that is precisely what the EPA pamphlet warns -- that regardless of ambient temperature, Extreme Heat Events (EHE) poses a serious health threat. Accordingly, EHE happens when the ambient temperature is not above 98.7F, i.e. normal body temperature. See p. 10 of the pamphlet for that -- the ambient temperature of Paris in 2003 never went over 100F in June and July, but the conditions were still considered EHE.

If the temperatures were somehow so hot that your body couldn't produce sweat fast enough to keep up with the fan, you would have died of a heatstroke anyway regardless of whether the fan was on or not.

Did you even read the post?

Now as for dying because the fan took away all of your bodily fluids, well that's just because you weren't drinking enough...don't blame it on the fan.

If a person who would not have died without a fan does die when with a fan, how is the fan not to blame in some respect?

So if the fan is cooling you down by circulating the air, at the expense of making you sweat, it just seems to me like the preventative solution is to just to drink more water and stay cool by keeping the fan on.

We have not witnessed anybody die from fan death, nor do we have any sort of physical evidence of it yet. Therefore, your explanation is speculation at best - it is far from scientific proof that fan death exists.

Right now, few in the world disputes Stephen Hawking although no one has witnessed the Big Bang and no one has seen any physical evidence of Big Bang -- only a number of phenomena consistent with with the theory of Big Bang. So is Big Bang the same kind of "speculation" as the yeti?

To put it in different words, you have to realize that “proving” something COULD happen proves nothing.

You want a scientific explanation? The Korean already gave it, but here he will summarize again.

1. Heat stroke can happen at high temperature and high humidity, which occurs in Korea.

2. If you point a fan directly onto an object in a hot, enclosed chamber, the temperature of that object will rise faster than being in a hot, enclosed chamber without a fan. The mechanism of a convection oven proves this.

3. Also, fan directly on a human body depletes sweat faster than being without a fan. This is so not only because the added, drier air is pushed onto the body, but also because wind chill in high temperature makes the body feel like it is sitting in a higher temperature. This is also scientifically proven.

When the causal mechanism is scientifically clear, it is unscientific not to accept the result that the causal mechanism generates. Especially when preconditions leading up to Fan Death is identical to what Korean people perceive as dangerous, and also consistent with what Korean media report as Fan Death.

And if that's not enough, the EPA and a climatologist who works for NOAA specifically warn people not to use fans in high temperature. See p. 16 at the EPA pamphlet ("hot dry winds can also increase heat index values."); p. 37 ("Because of the limits of conduction and convection, using a portable electric fan alonewhen heat index temperatures exceed 99°f actually increases the heat stress the body mustrespond to by blowing air that is warmer than the ideal body temperature over the skinsurface); p. 51 ("DON'T direct the flow of portable electric fans toward yourself when room temperature is hotter than 90F").

I must admit, your misunderstanding of simple logic is somewhat frustrating. Your "proof" from the EPA is not proof at all, instead, it is anecdotal evidence. Let me explain:

If I were to set out and try and prove that normal rain water can melt human skin, I would be hard pressed to find any quotes where people make this claim. If I were to, however, use a quote saying "experts claim to not go out in thunderstorms" as my evidence for proving that rainwater will melt skin, this would be anecdotal evidence. That is to say, it is not a direct confirmation of my point. When you say that people claim "not to point fans on yourself while you sleep at night", you do not prove that fans can kill. If the EPA said "fans pointed at you at night will result in death", THEN you would have real evidence. Your quotes are simply you not understanding what real evidence is.

Aside from that, all you have done is restate the same thing you said in the article, which I explained to you in full detail was not real science, it is SPECULATION, i.e., you speculate that these principles combined together can cause fan death, yet you have not PROVED it.

What your article does is disingenuous in the fact that you have not actually proven fan death, yet you claim to have done so. Furthermore, it is irresponsible for you to spread this misinformation, as you can cause people to believe something that is not real. You could potentially kill somebody by convincing them to not use fans in hot weather when they HAVE been proven to prevent heat stroke.

I know this has nothing to do with your article, but just to clear up:

"Right now, few in the world disputes Stephen Hawking although no one has witnessed the Big Bang and no one has seen any physical evidence of Big Bang -- only a number of phenomena consistent with with the theory of Big Bang. So is Big Bang the same kind of "speculation" as the yeti?"

There IS physical evidence for the Big Bang. One such example would be the measurement of radio source counts which cannot work with any other model of universe creation. This is just you simply not doing your homework.

Furthermore, it is logical fallacy to claim that, since Stephen Hawking said it, it must be right. Though he is brilliant, is an expert on this matter, and I do agree with him in this instance, he is human and he can be wrong. Please stop committing errors of logic, it is only hurting your argument.

If I were to, however, use a quote saying "experts claim to not go out in thunderstorms" as my evidence for proving that rainwater will melt skin, this would be anecdotal evidence.

Read the EPA quotes again please. For example: "Because of the limits of conduction and convection, using a portable electric fan alonewhen heat index temperatures exceed 99°f actually increases the heat stress the body mustrespond to by blowing air that is warmer than the ideal body temperature over the skinsurface."

The EPA is talking about the EXACT SAME causal mechanism that the Korean discussed all along, and nothing like the relationship between "rain melting skin" and "don't go out on thunderstorm."

You could potentially kill somebody by convincing them to not use fans in hot weather when they HAVE been proven to prevent heat stroke.

It is not the Korean, it is the EPA: "DON'T direct the flow of portable electric fans toward yourself when room temperature is hotter than 90F."

There IS physical evidence for the Big Bang. One such example would be the measurement of radio source counts which cannot work with any other model of universe creation.

Go back to your reindeer example. You were saying that even if you scientifically prove every step of the causal mechanism through which reindeer could fly, nothing is scientifically "proven" until someone actually sees a flying reindeer. The Korean is only working within your example -- no one actually saw the Big Bang. As you said (AND as the Korean noted,) there are only phenomena that are consistent with the theory of Big Bang (i.e. radio frequency.)

Also, being disrespectful only hurts your persuasive capital. The Korean had The Brief History of Time on his lap as he wrote that paragraph.

2. Fan directly on the body in high temperature in an enclosed room makes the body feel hotter.

3. Therefore, fan directly on the body in high temperature in an enclosed room makes heat stroke more likely.

If you want to argue against fan death, you have to argue against some part of this. Other commenters have done so, and respectfully. The Korean expects the same from all objectors. If you so care about science, argue with science -- not with Bartlett's.

It's disturbing that no matter how obvious your logical fallacy is, you refuse to admit ANY mistakes that you have made. You still have not SHOWN that fan death is real. Period. I don't mean it to be disrespectful, you are interpreting it as such. I see no study, I see no experiment. Everything you have said is purely speculation.

Furthermore, any scientist worth their grain in salt will tell you there is observable evidence for Big Bang. Otherwise, trust me, nobody would believe in it. The fact that you don't understand modern scientific concepts is telling. Just because nobody saw the Big Bang doesn't mean we can't see evidence of its existence after it happened. Just like when nobody sees a murder happen, we can still prove it's happened with evidence after the fact. Knowing how, so far, you have not understood basic concepts, I would speculate you have not fully understood "The Brief History of Time" after reading it.

One last argument: Out of three of the most respected independent medical agencies on earth - the American, European, and Japanese Medical Agencies - not a single one of them mention fan death as something which results in death in humans. So, either this has slipped under the radar of the greatest medical minds in the past few decades and you're the one enlightened individual in a vast sea of ignorance, OR the one who I would assume isn't a scientific expert in any sense of the term, you, is wrong. Which do you think it is?

Just because an argument is strong doesn't mean it is disrespectful. I have not called you "stupid" or any other name, I have simply expressed my frustration that you have not come to an understanding of my argument yet. I have been, and still are, willing to accept your ideas IF YOU CAN SHOW ME PROOF. You could even try it in your own home: turn on a fan in a closed hot room, and measure the temperatures before and after the fan has been on for a long time. That would at least be SOMETHING you could show to us to convince us.

Now, I am willing to admit that perhaps the reindeer example was not as clear as it should have been. I seriously want you to understand what I am trying to tell you, so I'll explain it differently.

In order to prove reindeer flight, we would require observable evidence of reindeer doing so. This would most likely have to be watching a reindeer fly, but it could be done by other means. One such mean would be to find evidence, such as reindeer droppings, reindeer fur, or reindeer footprints in a location where the reindeer could have only possibly reached by flying. All of that is appropriate evidence.

With Big Bang, the reason it is a theory but not a law, and not speculation, is because we do have observable evidence for it, but you're right, nobody has "seen" the big bang. With that being said, we still do not have observable evidence, be it first hand or second hand, of fan death or reindeer flight, which is why the mainstream community has yet to believe in them.

It would appear as if you're not going to respond to my comments anymore. In light of this, I would say that I have failed you, and I apologize for that. Reading through the comment threads, you appear to be a smart, balanced, open-minded individual! Which is why I tried to argue you in the first place. It is RARE to find people on the internet who will willingly post the comments of dissenters!

With that being said, I have simply presented the cold, hard facts as I see them, and I apologize if you have viewed that as derogatory. Being told you're wrong is something nobody ever wants to hear, and I applaud you for allowing me to present my ideas. I once sat where you sat now, trying to defend beliefs I held from a great number of people - the world community, in fact - who disagreed with me. It was a long process, but I eventually came to the realization that even things I believe in strongly should be viewed critically, and have since stopped believing in those things.

Keep in mind, I don't say you're wrong simply because of this. I encourage you to investigate your claims further! The world needs more people like you who are willing to dissent with the main stream: that's how breakthroughs are made! It seems like I won't change your mind any time soon, but I wish you a thought-provoking, insightful journey into the investigation of fan death in the future, if you so will to do it! It is through those kinds of journeys that we can all grow as people, and since you are already an impressively thoughtful individual, I would say you're already well on your way to becoming somebody we can all look up to!

It would appear as if you're not going to respond to my comments anymore. In light of this, I would say that I have failed you, and I apologize for that.

Giving up so soon? Just because the Korean would prefer watching football over replying to comments on the blog?

I have been, and still are, willing to accept your ideas IF YOU CAN SHOW ME PROOF. You could even try it in your own home: turn on a fan in a closed hot room, and measure the temperatures before and after the fan has been on for a long time.

That much shows that you probably didn't understand the Korean's argument in the first place, since the Korean said multiple times that the ambient temperature does not rise because of the fan. What rises due to the fan is the body temperature.

But if you want to see an observable fact consistent with fan death, try what commenter -pat. suggested. At temperatures of 90F or higher, wind chill increases the heat felt by the body. More thermal stress on the body = more likelihood of heat stroke.

One last argument: Out of three of the most respected independent medical agencies on earth - the American, European, and Japanese Medical Agencies - not a single one of them mention fan death as something which results in death in humans.

Interesting. So what you are telling me is:

- You can read Japanese at a level enough to decipher medical journals, and possibly other European languages, and

- In the six hours between the Korean's last comment and yours, you managed to scour all available medical journals from two countries plus the European Union. An amazing feat, given the huge number of medical journals.

The Korean will repeat, for the last time: the Korean already presented the science of fan death. You can argue against it, as other commenters like Gomushin Girl and P. Dishy did. Again, if you care so much about science, argue with science, not with some BS argument relying on "American Medical Agency."

While the scientific explanation presented here is certainly plausible, the few epidemiological studies on whether or not electric fans are a contributing factor in any heat-related deaths are inconclusive. In fact, a quick search of PubMed reveals only two studies (both linked to in the Wikipedia article on “Fan Death”) that cautiously conclude that electric fans are not a significant contributing factor in heat-related deaths. Keep in mind that in the field of medicine, many phenomena appear to be biologically or chemically plausible but end up having little to no actual clinical effect (i.e. it could be the case that electric fans operating in an unventilated room during an extreme heat event do raise the body temperature and hasten sweat evaporation, but the real question is by how much. It might be that while this effect does occur, the increase in sweat production and increased body temperature are not biologically significant). This topic requires further study, and it’s a bit premature to declare that “Fan Death is Real” in the absense of any well-founded studies.

In all actuality, the real danger of using an electric fan in an unventilated room during an extreme heat event is probably the false impression that the fan is doing something to cool the body, which leads people to forgo the use of other cooling systems (A/C, opening windows, etc). Again, we don't know what's really going on here, and I hope further research is forthcoming.

Fan death is possible,though i haven't heard news about this in the Philippines. And esp the suffocation part! If you are not a sound sleeper, you may wake up in the middle of the night because of the humidity and the stink due to closed windows...

Haha! I just confronted my bf about this because I hadn't ever heard of it and he was so serious about it being true. Then he googled it (navered it?) and realized there's no scientific basis for it. Then he questioned everything he thought he knew.

It was like telling a kid Santa's not real and watching the reaction. Nooooooooooooo! *runs away in slow motion*

I asked about poop mountain or poop and dreams. Have you heard of this? He had no idea what I was talking about.

I would like to challenge premise three ("therefore, fans make death more likely") on the basis of this large metaanalysis I found on Wikipedia: http://archinte.ama-assn.org/cgi/content/full/167/20/2170/IRA70009F3

The plot which shows electric fans have a small negative effect on the probability of death by heat stroke during heat waves is at the bottom right of Figure 3. So, electric fans do not increase the probability of death by heat stroke during heat waves.

Thanks Jeremy, but Fan Death skeptics are like cockroaches -- they just refuse to die no many how much truth you spray on them. The Korean badly wants the Mythbusters to test, but when (not if) Fan Death gets that big "plausible" sign on the show, the haters will find a way to continue hating.

This is an interesting article, but it fails to distinguish between something that "could" happen and something that "will" happen. Plausibility does not imply actuality.

Also, red wine actually is good for your health. It contains resveratrol, a powerful chemical which has anti-cancer, antioxidant and anti-inflammatory properties. It's been conclusively proven that moderate consumption of alcohol increases lifespan and reduces your chance of death.

I'm interested to know how many people in these exact conditions would have died without the fan. A drunk person trying to sleep in a room with a heat index of 99+ degrees F is a dangerous situation. If you omit the fan, and the person still dies, is it still fan death? There maybe be a correlation, but is it causal?

This is a really old post, but it actually doesn't look like anyone with much of a physics background has taken a hack at it. I just want to point out that while this explanation is largely accurate, this part is dead false:

"Keep in mind that Korea’s summertime routinely hits 90 degree Fahrenheit (around 31 degree Celsius). This means that although the room’s air temperature is 90 degree Fahrenheit, with a fan on, your body is cooking at the same rate as being in a room with 140 degree Fahrenheit (61 degree Celsius)."

Er, no. First of all, this "fan=30 degrees hotter" business is a vast oversimplification; the actual apparent temperature depends on the actual temperature, the geometry of the object and the rate of air flow. I suspect you know this and were simplifying on purpose.

But your simplification glosses over a rather important detail. Fans increase the rate of heat transfer between fluid (including water, whose higher-than-air heat conductivity is a separate phenomenon) and object, in whatever direction it would occur anyway . The air in the turbo oven is already hotter than the chicken, but the fan makes it seem hotter than it is.

In your closed room example however, as hot as the air may be it is not hotter than your body, except in very extreme cases. Hot as Korea might get, 37 degree summers are pretty rare I think (though if they did occur, fans might become lethal). Thus, except in these very very few cases, fans will cool the body and not warm it. No hyperthermia.

The subtext about not being fanatically suspicious of Korean beliefs is valid, though.

"What the Korean does know is this: Fan death is a form of hyperthermia, and hyperthermia can occur at ambient temperature lower than body temperature."

This is perfectly true, but irrelevant for subtle reasons. Hyperthermia occurs at ambient temperature lower than body temperature because the body produces more heat than it can safely retain. Therefore, it needs to be surrounded by fluid that is quite a bit cooler than itself in order to dissipate safe levels of heat. So suppose your body temperature is 37 degrees, and the air temperature is 33 degrees. You are the hotter object, so heat is flowing out from you into the air - just not enough to make up for all the heat your metabolism produces.

However, a fan blowing air at a temperature lower than that of your body will still cool you. This is because, as I said in the last comment, the fan accelerates the rate of heat transfer in whatever direction it occurs. As long as the ambient temperature is lower than your body temperature, heat is flowing out of your body, and therefore even more heat will flow out of your body with a fan on. 33 degree air holding still might not be able to dissipate enough heat to keep up with your metabolism, but moving 33 degree air might.

Actually, it seems P. Dishy has a pretty good understanding of what's up, though he might have emphasized the fact that what you're saying violates the second law of thermodynamics a bit more. And maybe, upon a second reading, I was being a bit diplomatic when I said most of your description was accurate. I'm particularly interested in how this "layer of cool air" knows to follow us around all the time, and in how we cool this air down without drawing heat into our selves or using telekinesis to force it into the air more distant from us. Evaporating sweat would, of course, warm the air.

I first learned about fan death from my husband's parents after the birth of our first child. Like Chris@8/17/09, my mother-in-law said something about the wind making "bad air". She also wanted the window or the door to the rest of the house(!) left open so that the bad air could escape. Being an American, I had an immediate allergic reaction to that and began to insensitively question her. She also claimed that the fan could freeze the baby - as in, actually freeze her, she wasn't just using the word freeze as an equivalent for cold - and that the baby could not breathe with too much wind. She didn't mention anything about heat though. Also, we have central A/C and it was on, but that did not satisfy her concerns. I wanted to share my story with you all b/c my mother-in-law is ethnically Chinese. And since we all know the Chinese invented/discovered everything ever, no doubt they created the idea of fan death and the rampant over-worry about it. So, you can blame them. They probably brought it over one of the times they came to visit.

"In fact, Korean people's belief is quite specific. They always speak of high heat, enclosed space, and the fan directly running on the body all night for death to occur. Non-Koreans hearing this concept fixate on the fan part, but Koreans themselves know better."

I'm from Houston, where temperatures regularly pass 90 degrees, the heat index is much higher because of humidity, and the temperature doesn't drop more than a few degrees at night. Every summer, several people die, usually the elderly. The media reports it, talks about the high heat, and then points to rising electricity prices as the culprit. (The deceased couldn't afford to keep their air conditioning running.) I doubt that Korean autopsies say "fan death," just like Houston autopsies won't say "insufficient AC."

Human body is not a regular "object." It self-generates heat. And unless cooled by sweat, rising body heat causes hyperthermia. This was dealt in the comment the Korean gave last year.

No it wasn't. It's true that another poster brought up a similar point, but you seem to have missed its importance (not that I'm expecting you to read comments on several-year-old blogs that carefully, but still - people still seem to fairly regularly reference this post, so it's still somewhat current, if not to you).

You seem to be saying: "the metabolism generates heat, and sweating dissipates that heat. Sweating does this by cooling the layer of air immediately surrounding the body so that heat leaves the body more quickly than it would otherwise. But a fan blows away that layer of cool air, so that the body is exposed directly to the hot air in the room. Normally, this cools you down because the body sweats more to compensate - essentially, the fan forces your body's cooling mechanism to run faster. However, this also means that the fan can quickly dehydrate you, and if this happens, it will leave you without your layer of cool air, so you will overheat".

This description, however, is wrong for several reasons. Sweating cools you because the sweat absorbs some of the heat in your body, then evaporates away, taking the heat with it. This warms the surrounding air, which has now absorbed some of the heat from your body - the "layer of cool air" that protects us all exists only in your mind.

Imagine a passed-out drunk guy in, say, 33 degree weather. As you correctly point out, his metabolism is creating heat, which if unchecked will raise his body temperature to intolerable levels. However, his body temperature is still higher than the temperature of the air, so heat is flowing out of his body and into the air - just not quickly enough to keep him cool. By sweating, he can accelerate the rate of cooling such that he survives the night.

How exactly does the heat leave his body? First, he warms up the layer of air directly surrounding himself. As that layer of air warms, the difference in temperature between him and it decreases, so the rate of cooling slows over time.

Now imagine the same situation with a fan on. The man warms up the layer of air directly surrounding himself. Then the fan blows that warm layer away - so the rate of transfer never slows. That is why the fan makes him feel cooler.

It shouldn't be too much of a stretch from there to see how a turbo oven heats: instead of blowing away the layer of warm air formed by cooling, it blows away the layer of cool air formed by heating; in other words it is the exact reverse situation as the fan, whether or not the object in question has its own heat source inside.

Once again: the fan speeds up the rate of cooling. It speeds up the rate of cooling both for objects that have an internal heat source, and for those that do not. Thus, a human with a fan blowing on them will heat up more slowly than they would otherwise, so the fan is not a cause of their death. Take the fan away, and they would be worse off.

the "layer of cool air" that protects us all exists only in your mind.

Then why is there wind chill? If there is no layer of air around us, we should feel the same way regardless of any air movement. But that is not so.

However, his body temperature is still higher than the temperature of the air, so heat is flowing out of his body and into the air - just not quickly enough to keep him cool. By sweating, he can accelerate the rate of cooling such that he survives the night.

Ok, so what happens when he cannot sweat as much any more because he is dehydrated? Seriously, this is already all dealt with in the 132 comments that precede this one.

Then why is there wind chill? If there is no layer of air around us, we should feel the same way regardless of any air movement. But that is not so.

Wind chill happens because the wind blows away the layer of warm air that surrounds you due to heat leaking out. This is the same thing that happens in a "hot" room during the summer - your body warms up the air as heat leaks out, but the fan blows the layer of warm air away, so you cool faster. What you seem to be missing is that all the heat comes from your metabolism; you don't take in heat from the air unless the air temperature is higher than your body temperature.

I was perhaps a bit hasty saying the layer of cool air was completely imaginary - this is sort of what is going on in a turbo oven. But the temperature in a turbo oven is (much) higher than that of the food being cooked.

Ok, so what happens when he cannot sweat as much any more because he is dehydrated? Seriously, this is already all dealt with in the 132 comments that precede this one.

I understand that you must be tired of dealing with comments on a post this old, but you really have misunderstood how this works. My point, and that of the more serious of the 132 comments above, is that the fan makes the person sweat less because it cools him down (people create more sweat to reduce their temperature, not to replace old sweat). It only heats him up, and makes him sweat more, if the air temperature is higher than his body temperature.

If the person is completely dehydrated, his temperature will rise due to his metabolism. The fan will slow this process by speeding up heat exchange with the air.

Now, look. It's clear from what you've written here that you're a smart person with little specific education on heat transfer - your description of convective heating/cooling is... questionable, and in the comments above you confuse heat with temperature. It's also clear from the rest of the blog that you're well-educated and well-connected. On the other hand, I am just some random from the Internet. So, here's what you should do: find someone you trust with a relevant education but no knowledge of fan death, say a physicist or an engineer or something, and send them what you've written, and what I or P Dishy have written, minus the specific mention of Korean culture.

There are a number of issues here that I think need to be sorted out because they are being just thrown together and preventing the debate from being resolved or resulting in both sides agreeing to disagree.

As a disclaimer, I will point out that 1) I am a biomedical engineer by training (BS, Northwestern University, 2006) and currently pursuing my doctorate in epidemiology at Michigan State (I am taking my comprehensive/qualifier exams in January, so hopefully I'm not far from getting onto my dissertation). I am Korean (specifically a gyopo or 2nd-generation Korean immigrant - and I never went through self-hate, though I did go through a similar contemplation because of my understanding of Korean history and how a large share of the shameful parts we brought on ourselves; though technically I qualify as a 1.5-er if you want to split hairs - I was born in Busan but moved with my parents to Chicago just before my 2nd birthday and grew up in the suburbs), but while my mother may have warned me at certain times some summers about the risks of having a fan blow directly on me in a closed room during the summer, I have never really put any stock into fan death, especially given some of the uninformed rationalizations attempting to explain the phenomenon.

Anyway, on to the issues that need to be separated and resolved - individually. The first is that this is a civilized debate, and that the issue is whether or not "fan death" is real. That in itself presents a number of problems. How do we define "fan death"? Are there specific parameters encompassing this, and what about those instances said to be "fan death" (and those rationalizations given) that fall outside our parameters? And what in the hell do we mean by "real"? I will agree to one poster who called the Korean out on the almost-sensationalism of the original post's title, but frankly, the only reason why that's a problem is because the Korean, while describing certain aspects of what we were to understand as "fan death," did not clearly specify limits and what to do about instances of what others call "fan death" that fall outside of our parameters.

The second issue is whether or not one agrees with the assertion, and why. There seem to be two major parties on why one would disagree: the first is that there is no empirical evidence, and there are no published studies, demonstrating the possibility of this phenomenon and by default this means the assertion is false; and the second takes issue with the physical (e.g. the thermodynamics, fluid mechanics, and so on - let's just call it the "science") details used to support the assertion. These parties should also actually be separated into distinct positions, for the very reason that the grounds for the first position has been conceded by the Korean. If this is the reason why one cannot accept "fan death," fine. Point conceded. End of discussion. It is reasonable to fail to reject the null hypothesis (i.e. that "fan death" does not occur) due to the lack of sufficient evidence. However, the grounds for this position do not necessarily negate the possibility that the alternate hypothesis (i.e. that "fan death" can occur) is impossible. Now, keeping score here: this is the first of two positions defining why one might disagree with the Korean's assertion (which I describe as a hypothesis, for reasons I will explain now).

I consider the Korean's assertion more of a hypothesis rather than a declaration of fact (which he conceded in subsequent comments by stating that under the precise conditions outlined in the original post a fan could be a contributing factor to death) because it is one possible theory (of several) that attempt to explain or rationalize why some people have died in the summer under conditions that included those that have been pointed out (closed room, hot day, fan blowing directly on sleeping person). "Fan death" just happens to include the fan as a potential risk factor for death.

The second position disagrees with the Korean's assertion based on the various physical details (e.g. the thermodynamics, fluid mechanics, and so on - let's just call it the "science") on which the assertion/hypothesis is based. This is a position on the basic theory of the hypothesis and not on the lack of empirical evidence. I personally think that the two positions should be kept separate, and if someone disagrees with the Korean's hypothesis due to both positions, they should be in two separate series of posts.

My position on this comes from what I see as another issue in this apparently endless debate: the undisciplined and often wanton use of half-baked (well, not all of them are half-baked) analogies and examples to bolster one or more positions. Because these analogies and examples are rarely perfect parallels and often not understood equally by all involved, they only tend to confuse the conversation, especially when people start resorting to pointing out flaws in other people's examples as a means of beginning to unravel those people's entire position(s). I think examples, even the carefully thought-out ones, should be kept to a minimum or not used at all, as they are usually only used in a feeble attempt to bolster the theoretical basis of one position or another but rarely do so successfully. Examples/analogies should be kept distinct, and discussions relating to specific examples should not be combined with discussions relating to other examples or even other aspects of the "science."

Other, less relevant, issues at play here are (which I believe have been alluded to by previous posters), I believe, an attempt at using "fan death" as commentary on Korean popular culture/urban legends, and an attempt at making (guaranteed to be flawed) generalizations about Koreans. I won't really discuss these except to say that these issues are irrelevant to the debate and should be kept out of the discussion.

I may not have said anything new in this post, but I am only laying out my approach to the whole issue that I will continue in the next post.

I am first going to define "fan death," its limits, what we do about instances that fall outside the parameter, and what we mean by "real."

I'll start with the easy one: what we mean by real, as has been expanded upon in subsequent replies by the Korean, is "scientifically possible, no matter how unlikely."

What do we define as "fan death," and what are the limits to this definition? I will go by the Korean's explanation of the specifics, i.e. instances of a human death immediately before which that human was sleeping in an enclosed room in very hot (I think the lower limit of our external temperature is 90 degrees Fahrenheit, or 32.2 degrees Celsius) ambient conditions with a fan blowing directly on his/her body. Conditions attributed to "fan death" outside these parameters, i.e. the person is not asleep, the fan is not blowing directly on the person constantly, the room is not closed, the ambient temperature is not as high as our lower limit, will be treated as not applicable and subsequent attempts to attribute deaths to "fan death" in conditions beyond these parameters will be subject to ridicule. Alternate explanations not adhering to these parameters will also be rejected (and also will likely be mocked).

Now, on to the major positions: 1. There is no empirical evidence to prove "fan death" within our parameters. This is true. Based on this, we fail to reject the null hypothesis, that "fan death" as we have defined it is "real" as we have defined reality, and the position that "fan death" is not "real" stands. But this does not mean that "fan death" is "impossible" due to lack of evidence, and should further evidence be provided in the future, we should reassess this position. But as it stands, on this and this alone, the hypothesis fails simply because there have been no clinical trials, no observational studies, and no otherwise-published convincing evidence that demonstrate this.

On the second position, the issues with the "science," I cannot necessarily take a hypothesis-testing position here, because it is not as if I can weigh the physical scientific rules against each other and come to one conclusion or another simply because it appears that more rules support a position on the phenomenon than another.

And while this would be much better-achieved with a schematic, I will try to keep this as simple as possible.

Let us imagine a thermodynamic system. For our purposes, this includes the immediate environment surrounding our enclosed room, complete with fan and dozing human. This immedate environment serves primarily as a heat reservoir/source to transmit heat to the room, because while the ambient environment may receive some quantity of heat from the room, it transmits a far greater quantity (by quantity I'm thinking in terms of Joules and British thermal units/btus). Every item in this system (there are five: the person, the room, the fan, the air in the room - which is for our purposes effectively disconnected from the air outside, and the ambient environment) is undergoing some form of heat transfer.

Everything but the human will start at our previously-mentioned lower limit temperature (32.3 degrees C; we'll assume that the temperatures of everything around have equilibrated). We will have to assume that the quantity of heat outside the room is infinite. Relative to the immense quantities of heat already present, the fan generates a negligible quantity of heat, nor does it undergo significant heat transfer due to its material properties for the temperature range we are discussing. In our scenario, the fan serves only as a means to move the air around. Because we have discussed this (despite it making a theoretical exercise more difficult), we must include a temperature gradient in the air from top to bottom, but let's for the sake of simplicity assume that this gradient is actually only two distinct temperature levels caused by the transmission of heat from the sleeping human (and the absorption of heat by the human's sweat from the lower air) to the upper air and from the transmission of heat from the outside environment to the air. As it turns out for our exercise, the physical room's contribution to heat transfer is negligible (though this is in reality not the case, and depending on the sophistication of your insulation may alter our result). So the primary physical objects undergoing heat transfer are the air, the human, and the outside environment, with the physical room serving only as a boundary between the air inside the room and that outside.

While I need to go eat and get some rest now, I will continue with this theoretical exercise later (hopefully tomorrow; I'll have to bookmark the page). We will need to establish some numbers for our hypothetical situation, including the mass of our human, the mass of air in the room, the flow rate of the air in the room due to the fan, and various quantities of heat present in the room at the start and quantities being transferred to and from various bodies. Some of these we will have to come up with on our own; others (such as the average quantity of heat transferred to an enclosed space of certain volume by an ambient temperature), we may be able to calculate.

I know I was attempting to portray an example with numbers, but even if I leave out a lot of detail and make a large number of assumptions, I have found that I would still need to look up lots of constants and the like, so I figure I'll put that off for the time being and just work with a descriptive example.

I also need to go into more detail on the particulars of our situation, namely that the body will have two separate parts of differing temperatures: the surface and the core.

Now, I am going to set up a new situation, and based on my understanding of various scientific principles, I am going to make a number of assumptions (which will be addressed qualitatively at the end of this current situation, and to a lesser extent quantitatively once I post my example with numbers, which I will have to work out on paper first when I can find the time).

The situation is this. Imagine our system to be a room shaped like a box. Six sides, twelve edges, eight corners, and so on. In this situation the material/insulation/etc. is unimportant because this is the entirety of our system and no heat will be exchanged between our system and some other environment outside it. The only elements in our system will be a sleeping human body (with a core temperature and a surface temperature), a fan, and our room (which effectively serves as the bounds of our system).

Assumptions: 1) the only way sweat is removed from the body is through evaporation (not, say, absorption into clothing or a mattress or anything like that); 2) the fan generates negligible heat and also does not participate in any heat exchange; 3) the human's core temperature is 37 C, but the human's surface temperature is 32.2 C, just like the air in the room; 4) there is no temperature gradient in the air at the start of our situation; 5) there is no heat exchange with any external environment, nor is there any air exchange with any external environment; 6) carbon dioxide suffocation due to the human's respiration in a completely sealed room is not considered; 7) the room is completely sealed; 8) the fan moves air at a constant rate; 9) the human has no source of hydration; and 10) everything else is normal (the human's physiology, material properties, and so on).

Now, in our system, the only source of heat is the human's body itself. If the human was not sweating before our thought experiment began, he/she will be when it does.

Here's what's going to happen. First, the sleeping human will sweat. Because water (I forgot to mention that we will assume that water's thermodynamic properties due to dissolved electrolytes will not change) is a much better absorber of heat than the human body, heat will leave the surface of the body and enter the sweat (heat, like a lot of things, moves from an area of high heat to low heat). In this way, the human will be able to remove heat from the body (because remember, the body's core is still producing heat and transferring that to the surface). Once the sweat's vapor pressure reaches that of the room (i.e. atmospheric temperature), it will evaporate, taking what heat it has absorbed from the body into the air.

Now here are some things we need to think about. Because the fan is moving air across the body, the air is not still. This means that the air immediately surrounding the body (we are not considering temperature gradients within the body itself either) will have a lower overall pressure (via Bernoulli's Principle; it's how airfoils work). This also means that the sweat surrounding the body will evaporate faster (because it will take less heat, and by extension less time, for its vapor pressure to reach the now-lowered pressure of the air around it), taking less heat from the body than if the air around it were still. This is not a huge issue, however, because the overall rate of heat transfer is initially much higher with the moving air than without it. This is because the fan is constantly pushing air across the body, each new volume of air containing less heat than the volume of air that was just pushed across the body and picked up evaporating sweat (this "old" air now has an increased quantity of heat because it has taken in the evaporated sweat, which had absorbed heat from the body's surface). This means that the rate of heat transfer from the body surface to the moving air around it is relatively high - so long as it is still sweating.

However, even when you're not sweating, you can lose heat to moving air because your body surface also radiates heat. When the air isn't moving, the rate at which this heat actually leaves the body and actually enters/is absorbed by the air is really small, and gets continually smaller because the still air around you has already absorbed some heat and will become increasingly resistant to absorbing heat from your body. However, when air is moving, the air around you is being replaced with new air that has not yet absorbed heat from your body and so the rate at which your body heat leaves your body and enters the air does not decrease as it would if the air was still. The reason why moving air feels even cooler when you're sweating or otherwise wet is because water is better at absorbing more heat (high specific heat capacity) from your body than the air, and because it is evaporating faster in moving air (just like thin layers of water evaporate before your eyes when you are, for instance, wiping your dishes down or washing your car and blow on the thin layers of air), it is taking this greater quantity of absorbed heat directly from your body and into the air.

Now back to the situation at hand. The air that is moving over the body and picking up evaporated sweat is not exchanged with any other air, it is not exchanging its heat with any other body, and it has also picked up heat in the form of your evaporated sweat, which has released heat into this air. Eventually the fan will recirculate this air over your body, and because it already has an increased quantity of heat, it is more resistant to absorbing heat directly from your body. Thing is, if you're still sweating, the movement of the air still reduces the air pressure around the sweat, and the sweat will still evaporate, releasing what heat it's taken from your body into the air regardless of how much heat is already in the air. Thus your body stays cool (and the air continues to gain heat) so long as you're sweating.

I think you can start to see the problem here. What happens when you stop sweating in a situation like this? All of the air is already heated from evaporated sweat, and despite the fact that it is still moving across your body, each little volume of air that is moving is more and more resistant to absorbing heat for the split second it moves across the body. Eventually it is imaginable that the only way heat leaves the body is through radiation, not convection. The rate of heat transfer via radiation is much lower, meaning less heat leaves the body per unit of time than before, to the point that most of the heat present in the surface of the body does not leave because the rate of radiation cannot handle the quantities of heat at the surface - the rate at which heat radiates from the body into the already-heated air begins to serve as a bottleneck, behind which Joules and Joules of heat begin to accumulate. Which means eventually, even if the human body is 60% water (and even if this water is distributed evenly between the core and the surface), because Q = mc∆T (or better yet, ∆T or the change in temperature = Q, the quantity of heat, divided by the product of the mass and specific heat capacity), the increased heat in the body's surface will increase its temperature. Because of this accumulation of heat at the surface, the core of the body will also have increased difficulty in transferring heat to the surface, and in time, for the same reason the skin's temperature increased, the body's core temperature will increase. If nothing changes, a human in this situation will die.

I've left something out here. So why is the fan at all a risk factor for death, when all we've done is effectively describe a specific type of heatstroke? In our situation, the fan initially served to rapidly cool the body while it was still sweating, but at the cost of continually heating up the air, probably well beyond the rate at which it would have normally absorbed heat from the body, radiation and otherwise. As soon as the body stops sweating, the circulation of the air by the fan does little to nothing for cooling. This leads to a rapid overheating of the body, which then leads to death. Without the fan, sleeping in such a hot environment will certainly be uncomfortable, but 1) the sweat will absorb more heat from the body before evaporating (though this becomes problematic if our room is humid, since the sweat will evaporate less and instead transmit heat back into the body if it has absorbed more than its capacity and hasn't yet evaporated), thus slowing the rate of sweat loss, and 2) if the air isn't moving, there will always be a place for the heat to go, because the air around and near your body will always have a greater quantity of heat than air that is further away (i.e. there is a heat gradient). The fan, while facilitating rapid cooling, also mixed the air such that there is no such gradient in the air. If the air is sufficiently hot enough though, it will transmit heat to the body instead of the other way around, so in this way still air can also cause problems. So there are two factors that are responsible for death in a hypothetical situation such as this: the air-mixing effect of the fan that prevents a heat gradient that can help take heat from your body, and the fact that your body constantly generates heat in such a closed environment.

Of course, all of this occurred under a large number of assumptions. Let us see what happens when these assumptions are violated, as they will likely be in real life. For starters, there will be at least some air exchange between the air in the room and air outside. So long as the rate of air exchange is low such that the fan is still largely recirculating the air in the room, there will still be problems. We assumed no heat exchange with any other environment. In reality this is not true (partially due to air exchange), but we must also remember that on hot days such as during the summer, heat not only leaves our little room but also enters it. If the quantity of heat entering the room is greater than the heat leaving it, we can still have problems. I did not explicitly say this, but I also assumed we had a small room. In a large room, the effects of what we have described would take too long to occur, unless perhaps one was in this room while in a coma.

At this time I should note that the "fan death" I described does not, like the Korean says, work like a convection oven. The only source of heat in our thought experiment was the human body (i.e. the item being "cooked"), and this is clearly not the case with a convection oven, which relies on an outside source of power to heat the hot air it blows around the food being cooked.

We assumed that suffocation from carbon dioxide would not occur. In real life, if you had a room even nearly as well-sealed as the one in our situation, you would certainly die from asphyxiation much sooner than fan-faciliated overheating (which in any real-life situation could take hours or days if it ever occurs at all).

I'm leaving out a number of the other assumptions (partially because I don't remember what they were), but I think you get the point. All of these things point only to the possibility, not probability, of fan death. As it turns out, the conditions under which fan death could occur are more likely to kill for other reasons than any overheating facilitated by the fan. However, this does not mean "fan death" absolutely cannot occur - for instance, the rate at which air exchange needs to occur for a human not to suffocate may not be sufficient to facilitate adequate heat transfer out of the room. It's just that our little situation has disproved the negative of "fan death is possible," i.e. it has disproved that fan death is impossible, albeit under highly unrealistic and improbable conditions. Just not impossible ones.

To clarify on the point of the vapor pressure: vaporization of water/evaporation of sweat can be effected by two independant principles - latent heat and vapor pressure. Independent of vapor pressure, if the heat (Q) added to water is equal to its specific latent heat (L) for a given mass (m) of water, it will evaporate. The mathematical relationship is L=Q/m. Independent of latent heat, if the vapor pressure of water is the same as that of its containing environment, it will boil (i.e. evaporate). What I meant by less heat being required to evaporate sweat in our thought experiment was that by adding energy (heat) to the sweat, we are increasing its vapor pressure (vapor pressure is actually related to a fluid's temperature via the Clausius–Clapeyron relation, but thanks to Q=mc∆T, we can draw a connection between the heat added to sweat and the raising of its temperature which increases its vapor pressure).

And to address the other assumptions: if sweat is absorbed into, say, clothing, or a mattress, the water will not evaporate from the fabric faster than it would have from the surface of the body, and thus the sweaty fabric will continue to absorb heat from the body instead of just evaporating into the air and doing no more heat absorption. The fan will generate some heat, but not in appreciable quantities, so this assumption actually holds in real life. The assumption that there is no heat gradient in a room is obviously not completely possible in real life, not even within an oven. The fan moving air at a constant rate is only there for when (if?) I do a more thorough example with numbers - it makes calculation so much easier.

There are some of the assumptions that, if violated, would pretty clearly invalidate our result. Obviously, if the human's core temperature isn't 37 C, there is something wrong, and if the human's surface temperature is lower than our lower limit of 90 F or 32.2 C, it will take somewhat longer for the surface to reach a high enough temperature that would limit or prevent heat transfer from the core to the surface. If there is a source of hydration (running water, large basin of cool water, etc.) in the room, it will be able to absorb heat from the air.

All in all, in real life, "fan death" as we have described it is unlikely, but because we have been able to demonstrate it in a highly unrealistic model, I suppose we should say that it is still possible, under the (highly improbable) proper conditions.

I'm kind of getting the sense that was an hilarious parody of my commenting style, but...

Basically what you have shown in ridiculously long-winded terms is that a human in a warm room who can't sweat will die. I know that. What I'm saying is that the fan will slow the process down, because the moving air removes heat via convection. It only can add heat to a body of higher temperature than the air. This is a direct consequence of the second law of thermodynamics.

You do raise the valid point that the skin temperature is actually the relevant quantity here, not the core temperature. But sweating doesn't begin until the skin temperature reaches 37 degrees anyway: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatreg.html#c1.

Basically what you have shown in ridiculously long-winded terms is that a human in a warm room who can't sweat will die. I know that.

I wasn't responding to you specifically, and I was just laying out the reasons why, since no one seemed to be able to explain why. I think the point on being dehydrated was also the point the Korean was trying to make earlier in the comments, which seemed to have been largely ignored. As for the long-winded part, I couldn't find a better way to 1) shut people up about something that doesn't matter anyway (clearly I failed), and 2) trying to work out the various details in such a situation required more than the 4000 or so characters to which you're limited per post.<&nbsp><&nbsp>I also made the point that the fan does prevent overheating initially - in fact, the only time it might stop doing anything for cooling is when you can't sweat anymore and the air contains more heat than your surface (i.e. is hotter than your skin).

As for sweating not beginning until your skin reaches 37 C, your source is quite wrong (and while citing a number of resources, it doesn't point a specific one out for that particular claim), and based on this study, that is clearly not the case. For confirmation, I suppose I'd have to consult my Stedman's medical dictionary, but I get the feeling that it won't give specifics precisely because there is no specific temperature or set temperature threshold for sweating; sweating is a physiological response for thermoregulation, and, like many physiological responses, it can be manipulated or anticipatory (for instance, you can sweat when you're nervous, angry, drinking coffee, or eating spicy foods, despite not actually being at 37 C anywhere on the surface of your body).

I already explained precisely how convection worked in our thought experiment, but you seem to have missed the point that in our experiment, after you've stopped sweating (which was the primary means of cooling; after a while it wouldn't be convection, but instead the lower air pressure due to air movement, that would allow sweat to still evaporate even though the air became hotter than the skin) when there is more heat in the air than there is on the skin surface (i.e. it's hotter than the skin thanks to the evaporated sweat, which transferred heat to the air), even if it's moving, the air will stop taking heat from the body except through radiation, which expels heat much more slowly, so much so that the skin is more likely to start overheating at this time. Moving air (especially in closed systems like ours) does not always cool things down (you seem to think that it does, though you forget that heat transfer works both ways), and it is this fact that allows convection ovens to work.

It only can add heat to a body of higher temperature than the air. This is a direct consequence of the second law of thermodynamics.

No, it is not. First of all, the 2nd law of thermodynamics states that over time, differences in potential (i.e. gradients) will equilibrate (as in the gradients will disappear) in an isolated system, like the one in our thought experiment. Entropy only increases, and thermodyamically, a system cannot fully recover the energy it expends (i.e. it cannot be 100% efficient). The 2nd law of thermodynamics is essentially a law of diminishing returns for a system that starts at disequilibrium. However, the time scale on which this would occur completely for our particular situation is much larger than what we are looking at (years at least, as opposed to hours and days, if at all).

The fan only adding heat to a body of higher temperature than the air would be a direct violation of this, not a consequence thereof. Sure, gradients can be generated for useful purposes, but they are always expended - there is no such thing as an eternal gradient, just a very long-lasting one. But this principle is not actually very applicable to our situation, because we have a heat-generating item (the human body) in our short-term system. To apply the 2nd law of thermodynamics, we would only be proving the point that eventually the human would stop generating heat because he/she was completely decomposed, the fan would stop moving air because it was no longer powered, and any energy in the system would have been dissipated into the universe, to help it expand, I suppose.

This was the point of the thought experiment, which might have been lost in the sea of text I've posted over the past few days: "It's just that our little situation has disproved the negative of "fan death is possible," i.e. it has disproved that fan death is impossible, albeit under highly unrealistic and improbable conditions. Just not impossible ones." Also "...in real life, "fan death" as we have described it is improbable, but because we have been able to demonstrate it in a highly unrealistic model, I suppose we should say that it is still possible, under the (highly improbable) proper conditions."

And again, the time it would take for such a phenomenon to occur would be on the scale of at least several hours for a small room, possibly several days for a large room, and that's if nothing changes (which for the large room could only be possible if you were in some sort of trance or a coma) and the unrealistic assumptions we made hold. I agreed with, and explained the theoretical science to, the fact that the fan, for most of the duration of the experiment, would serve to cool, not heat, the body. "Fan death" as I define it would end up occurring in a relatively short time at the end of our thought experiment, ostensibly after several hours have already passed. And this also assumes that you're well-hydrated (with lots of sweat with which to heat the air); if you stop sweating relatively quickly (for instance if you were very drunk or were somehow otherwise dehydrated when our experiment began), and the air is still cooler than your skin, the rate of heat radiating from your body to the air will be higher than it would be had the air been hotter (i.e. contained more heat), and convection will still be able to take heat away from your body.

And no, I wasn't intentionally trying to parody your commenting style. But maybe it was subconscious after having read some of yours.

I think a similar point could be made about your understanding as well (because again, moving air does not always lower temperature or take heat away via convection as you seem to insist, but can also transfer it to a body via convection.

Well duh. Moving (or still) air raises the temperature of cooler bodies. It lowers the temperature of warmer bodies. That's why pies cool and drinks get warm. What do you think the difference between the pie and the drink is?

There are a number of differences, unrelated to temperature, that also affect the heat transfer occurring in those objects. Density, the fact that they're at different phases (solid versus liquid), different material properties...the list could go on. That doesn't mean a thing.

I may have been wrong about the temperature sweating starts at.

No, it's not that you might have been wrong; you were absolutely wrong, and so is your source.

No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature.

That not only does not end the discussion as you claim it should, that helps demonstrate the phenomenon we observed (rather, expected) in our little experiment. You might recall that thanks to sweat evaporation, the body (whose surface started out at the same temperature as the air around it but whose core was at a higher temperature) added heat to the air around it, which was being mixed thanks to the fan. Because of other properties related to evaporation, the sweat continued to add heat to the air before the body ran out of sweat, at which point the air could have become more heated than the body, after which the body overheated. This, of course, is not the sole result of the entire process; over time, this process will end, the human will decompose, the fan will stop, the air will stop moving, and the entire system will lose all its heat to the universe, but during our time period of interest, which is different (read: much smaller) than the time period to which an appropriate application of the 2nd law would apply, the person could die. This is the whole point.

Clausius' wording could also be violated, in the way you present it, in the event that a refrigerator (or better yet, a freezer) is kept running outdoors, on a hot summer day. Either of these things add heat to the air around it (which, on a hot day, would have a higher temperature than the appliance) in order to keep what's inside cool. However, the time scale on which this occurs is still smaller than that in which the 2nd law would apply to that situation. Eventually, of course, the refrigerator and freezer would fall apart, stop working, and equilibrate with its surroundings. But not for the immediate future, unless maybe the power went out.

A lot of this discussion is dependent on time and rates, which cannot be ignored for situations like ours which do not have universal applicability.

The second law of thermodynamics, mathematically, involves differential equations, which, on a very basic level, are statements on rates and time and their effect on the ultimate outcomes of processes.

Looking at the Wikipedia (great source, I know :P ), I see that there's a note following the Clausius statement of thermodynamics, which has apparently been ignored (I personally already assumed this, but it is easy to forget): "Spontaneously, heat cannot flow from cold regions to hot regions without external work being performed on the system...." The definition of "spontaneous" here is the scientific one, which describes the movement of a system to an ultimate state of lower energy over time. This is not a description of how quickly that process takes place. In the grand scheme of things, the return of human metabolic processes to equilibrium (i.e. the human's death) is in fact a spontaneous process, which can be accelerated by a number of other factors, including the circumstances of our little experiment.

Here's the point on external work - the air is being heated, despite being at the same (or, later in our experiment, at a higher) temperature than the body, because work is being done on it by the body's metabolic processes, which radiate heat, by the sweat, and by the fan (which helps to evaporate the sweat, which itself has absorbed heat from the body surface). This is why the events in our situation are possible. Eventually the sweat will stop doing work on the air because there is none left, and the balance of what is doing work on what will turn in favor of the air doing work on the body surface. Over a great period of time, of course, the body will stop working, as will the fan, but looooong before then the human in our little room will be dead.

There are a number of differences, unrelated to temperature, that also affect the heat transfer occurring in those objects. Density, the fact that they're at different phases (solid versus liquid), different material properties...the list could go on. That doesn't mean a thing.

Okay, then make it a hot pie and an otherwise identical cold one. You can even have the air moving over both pies if you want. Why does the hot pie cool and the cold pie warm?

Charles, I appreciate your thoughtfulness. However, you're being led astray by taking "heat" and "temperature" to be all but synonymous. You seem to be worried about an accumulation of "heat," whereas you really need to think about temperature changes and gradients.

And your example with the fridge is wrong. Heat always moves from hot to cold. With your fridge, heat spontaneously moves from the hot coils on the back of the fridge to the less-hot air. Second law still holds here.

The main problem, as Adam points out, is that no one has yet provided a reasonable explanation for how a fan might SPEED UP heat stroke in a room that's below body temperature. I don't think anyone argues that people can't get heat stroke in these conditions. But the pro-fan-death contingent seems to argue that a fan somehow makes you waste sweat--that it makes you use it up too fast. There's no theoretical or empirical basis for this claim.

Once again...over the time that the person is sleeping, they create a certain quantity of heat via metabolism. They also have a fixed quantity of sweat capacity. This sweat can remove a fixed amount of heat, because the heat of evaporation of water is approximately constant at conditions we're considering. Since the fan doesn't change how much heat is created, and doesn't decrease the amount that can be removed by sweating, it simply cannot lead to a net accumulation of heat in the body. It's a simple energy balance thing.

I live in Singapore, and over here, as part of our tropical climate, it is ALWAYS above 30 degrees celsius (30-31) all year round, even during the rainy season, which also makes it 80% to 100% relative humidity, all the time. In fact, dehydration and heat-stroke is a problem in our region, where people get stricken with these conditions when they do not hydrate themselves properly. The British SAS in fact, sends their recruits to Borneo for jungle survival training, even before Arctic training.

If fan death is supposedly a 'phenomenon' in a region where 31 degrees is the peak temperature but ONLY in the summer season but absolutely unheard of in my country and neighbouring ones where 31 degrees C is temperature almost all of the time, then to me that's one big nail in the coffin for this.

I cannot afford air-conditioning, so I use an electric fan, and sometimes with loud noises coming from the outside, I would close the windows and obviously, allow the fan to run on full blast because it's always warm and uncomfortable. And so far, I've never once turned the fan off in the middle of the night because I'm dehydrated or hot.Yes, it does become stuffy but it's tolerable, and I'll usually open the windows up a few hours after realising that they were closed.

I also would like to have some input on the perspiration part, so if it was done already I apologise, for I do not have the strength to search through all the comments for it. As already mentioned, humans sweat to help them cool down, as when sweat evaporates, it removes heat from the body. Once the body cools down to a certain point that the bodily mechanisms feel its comfortable enough to function without causing perspiration, perspiration should ease.

Now, I don't get the point of 'fans repeatedly blowing hot hair onto the body, causing the body to repeatedly sweat till it dehydrates'. Due to the simple laws of thermodynamics, heat will travel from a warmer region to a cooler region. Even though the air temperature may be 31 degrees C, if the human body temperate is at the normal 36.5C to 37+C, the ambient air will draw away temperature from the human body, no matter the rate of heat exchange, no matter if its moving wind or not.

I think of the human body like a heat sink, where heat is released from a solid medium to a fluid medium, in this case referring to air. I need not explain that moving air should be more effective in reducing temperature of the solid medium, provided its temperature is lower.

Thus, I don't see why circulating air from a fan in an enclosed space would, based on the explanations I gave above, to overheat and require continuous perspiration to regulate body temperature and resulting in dehydration, unless it can be proven that a direct-blowing fan on a human being can raise temperatures in the room. Also, because the human body will continue perspiring until it reaches a point of comfort, where the body mechanisms stop sweating. Thus, under the conditions I mention above, the body would eventually cool down and cease perspiring, and I don't see how a human can continue perspiring till the point it dehydrates, unless one can prove that continuous fanning would cause ambient temperatures to rise close or above bolidy temperatures, which would invariably cause the heating up of the human body and hyperthermia, even up to 104 F.

However, I find the 'turbo oven' example dubious. From another perspective, turbo ovens are designed to work as efficiently as possible, so variables causing are reduced, insulations are used and heating elements and other design-related attributes are optimized for efficient convection currents. Thus, a turbo oven has the ability to cook food even under relatively low temperatures, and with that I feel that a residential room cannot be compared to the heating potential of a turbo oven. There are too many variables for heat equalization, with draughts in the windows and doors, and heat loss through other means. Thus in my opinion a standard residential room is too inefficient for a convection current to occur, resulting in an acute increase in ambient temperatures.

1. Heat stroke can happen at high temperature and high humidity, which occurs in Korea.

As mentioned with reference to the climate of my country it is worse in my region's case but in the absence of such a 'fan death' phenomena, this point is unable to support your big idea that 'fan death' is, regardless of its magnitude, a problem.

2. If you point a fan directly onto an object in a hot, enclosed chamber, the temperature of that object will rise faster than being in a hot, enclosed chamber without a fan. The mechanism of a convection oven proves this.

Because you confused basic thermodynamics (temperature of solid medium i.e. human body vs temperature of fluid medium i.e. ambient temperature) and a poor use of the convection oven, your argument is rendered invalid.

Also to highlight is your glaring issue in not providing proper citations to prove your point that 'fan death is real'. Many commenter have already went through this problem ad nauseum, but I'll take a different perspective on it.

From a perspective of objective research, if this issue is of a concern, a researcher must be confident that it applies to a certain percentage of a population, be it Korean, international or whatever, and it should be a clear majority percentage; for scientific research it's usually 99%. At this point you might say that from the citations you mentioned, this problem applies mostly to elderly and children, who do not regulate their body temperatures well (quote: "Elderly, children, and people sleeping drunk are at the greatest risk"). However, from the phenomenon as we know of, fan death is a widely held belief by Koreans, which is reflected by the kind of electric fans sold there, which from what I know, are almost all equipped with shut-off timers. This show that Koreans of a variety of age groups, adults, believe that this problem applies to them, not just elderly people and children. Thus, even though you were able to provide some supporting facts to show that this problem applies to elderly and children, you were not able to account for much of the rest of the Korean population, to show that this problem is a significant one which people should be aware of.

However, you did admit that it is actually not a huge problem, being more of an isolated one (quote: "Fan Death in Korea is a rare and unlikely event. Even including the "false positives" reported in the media, Fan Death is not reported any more than once or twice every summer.), in which case I think that's the point: it is such an insignificant problem, where others have already explained well that there are more significant ways for people to be put in danger, the media has clearly shown to be unable to provide clear and concrete evidence of a phenomenon that is resulting in the clear deaths of people due to fans operating in enclosed spaces, and that there is insufficient scientific research which shows a correlation or causation of fans and deaths, not only is this issue difficult to prove, because scientific research is done on a phenomenon because it is determined that this issue applies to a large enough group of people for the proposed research to be significant and that the research will be of benefit to humans and scientific knowledge, this phenomenon in my opinion is not only dubious, but is also an insignificant problem that even if there are any deaths resulting from fans in enclosed space, these cases should be considered more as isolated, closed incidents which do not apply to the general population.

Therefore, I am of the standpoint that the idea of fan-related deaths in Korea must fall.

To recap most importantly, I am a Singaporean, living in a tropical climate 30C in temperature, 80 R.H. and above, 24/7, 365 days a year, and we have not seen any significant issues of fan-related fatalities.

However, you're being led astray by taking "heat" and "temperature" to be all but synonymous.

That's because they (almost) are. Basic thermodynamic rule: Q = mc∆T. To be fair, this equates heat to the change in temperature, but my point is that they quite often are analogous (not necessarily synonymous), and can be treated as such in our situation.

...no one has yet provided a reasonable explanation for how a fan might SPEED UP heat stroke in a room that's below body temperature.

I did, but I suppose it was buried in the copious volume of my comments. What happens when air moves rapidly over a surface is that the air pressure over that surface is lowered (Bernoulli's Principle); specifically, when there's a difference in the air speed above a surface and the air speed below a surface (this is how airfoils work - air is required to move faster over the top of an airfoil, reducing the pressure or force per unit area above the airfoil, which at sufficient speeds generates lift). When we are discussing a human body that is sweating, this means that the air pressure immediately above the body has decreased. This lowers the evaporation threshold for the sweat on the body (sweat evaporates when its vapor pressure is equal to that of its environment, which in this case has been lowered by the movement of air over the body).

But the pro-fan-death contingent seems to argue that a fan somehow makes you waste sweat--that it makes you use it up too fast.

This is exactly what would happen in such a situation. This is why sweat evaporates faster from your body when it is moving in air or air is moving around it, and this is why fans are so great for cooling - so long as you're hydrated, you will continue to sweat, and even though it doesn't absorb all the heat it has capacity for, it will evaporate rapidly instead of radiating any of the heat it has already absorbed back into the body.

With your fridge, heat spontaneously moves from the hot coils on the back of the fridge to the less-hot air.

We don't know that the air is less hot. And I never set that up as an example of how the second law might be violated; I was using it to point out to Adam that in his very narrow (and inappropriate) application of the second law, a refrigerator might seem to violate his interpretation of the second law, when, as you have aptly pointed out, it does not.

Since the fan doesn't change how much heat is created, and doesn't decrease the amount that can be removed by sweating, it simply cannot lead to a net accumulation of heat in the body. It's a simple energy balance thing.

No, the fan doesn't change how much heat is created, it doesn't affect how much can be removed by sweating, but you are wrong in believing that this cannot lead to a net accumulation of heat in the body. And no, it's not an energy balance thing. Even after the sweat has removed the maximum possible amount of heat it is capable of absorbing, this does not mean the body has stopped doing anything but sweating. The body will still generate heat afterwards (it's not as if cellular respiration and the breakdown of ATP has stopped simply because you stopped sweating), and this heat will not be able to leave the body nearly as efficiently, to the point that the body will overheat if nothing is changed.

I would recommend to anyone who has something to say in any attempt to counter what I have said: read the entirety of my comments (long, I know - but the science behind this is not as simple as everyone seems to think) before trying to make some simple attempt to nitpick at pieces of individual comments taken out of context.

And as I've repeated over and over again, in spite of everything, I still am quite skeptical that something like fan death could ever actually occur in the real world, but in theory, it cannot be ruled out.

I'll usually open the windows up a few hours after realising that they were closed.

In our discussion of fan death, it occurs so long as the room is sealed indefinitely (at least until the time of death). You opened your windows, so your personal experience would not apply here.

Due to the simple laws of thermodynamics, heat will travel from a warmer region to a cooler region.

This is not always the case. As our lengthy example has indicated, air pressure is lowered when air moves above a body, thus lowering the threshold pressure at which sweat can evaporate. This is why your sweat evaporates faster when you have a fan running.

This example does not operate like a convection or "turbo" oven. As the source of heat in our hypothetical example (see my comments above - I know it's a lot, but it should be easy reading) is the human body itself, this is not how a convection oven works.

Because you confused basic thermodynamics...and a poor use of the convection oven, your argument is rendered invalid.

That is not a logical basis on which to invalidate or dismiss an argument out of hand.

Therefore, I am of the standpoint that the idea of fan-related deaths in Korea must fall.

To recap most importantly, I am a Singaporean, living in a tropical climate 30C in temperature, 80 R.H. and above, 24/7, 365 days a year, and we have not seen any significant issues of fan-related fatalities.

I still do agree with you that "fan death" as some kind of widespread phenomenon is false, but not for the reasons you say. In my example made in my comments, I made a number of possible (but unrealistic) assumptions, which, if sufficiently violated, would nullify the effects of the experiment. Therefore, I reasoned that since my assumptions would almost always be fully violated, "fan death" as represented cannot possibly be as frequent as reported. However, because it was possible in theory, we cannot say that it is "impossible."

As for "significant" issues of fan-related fatalities (I'll assume you only mean fan-facilitated as opposed to "physical trauma through contact with moving fan blades"), I would be careful with that wording. Do you mean the number of fan-related deaths is not statistically significant (i.e. is there some p-value cutoff which has not been met)? Do you mean that there are such fatalities, but so few as to not be significant in terms of public/social concern? While I do understand what you are trying to say, I hope this illustrates how your statements can be misunderstood.

A refrigerator is a heat pump. It moves heat against the gradient by doing work on a gas - heat going from cold to hot is not the sole result. A fan is not a heat pump.

The fan speeds up evaporation of sweat. It doesn't speed up production of sweat, so it can't make you use up sweat too fast.

It also doesn't make you overheat faster than you would otherwise after you've run out of sweat, as long as the air is cooler than your skin. In this case the fan will slow down hyperthermia, though it may well still happen.

(Change in) temperature is only equal (and even then not dimensionally) to heat when the mass and heat capacity of the two systems being considered are equal, which is obviously not true here.

True, but what about the body? It still generates body heat regardless. The sole result of this, too, is not the transfer of heat from cold to hot. Ultimately, the person in our thought experiment dies, at which point body heat generation ceases and everything in the body goes to equilibrium (well, it decays, but it goes to equilibrium first).

The fan speeds up evaporation of sweat. It doesn't speed up production of sweat, so it can't make you use up sweat too fast.

It might not directly speed up production of sweat, but when the sweat leaves the body, so long as it is still hot, it will continue to produce sweat to replace what sweat has been lost - the faster the sweat evaporates, the faster sweat is produced to replace it (so long as the body remains hot; obviously this is not the case if the sweat has done its job and the body has cooled down). Initially, while a person is still cooling down (i.e. is still too hot), an increase in evaporation rate will (because the body still needs to cool itself) will lead to a corresponding increase in the rate of sweat production/excretion, until the sweat is no longer necessary or there is no more water, urea, etc. with which to produce sweat.

...as long as the air is cooler than your skin.

I guess this is the sticking point, really - in our hypothetical situation, it turns out that the air is hotter than the skin, because the body continued to generate heat, which was released into the air by evaporating sweat; this heat never left the room because we assumed that there was no heat transfer into or out of the room (improbable, I know - I address the improbable nature of many of the assumptions made for our hypothetical situation as well; however, on a hot summer day, it is quite reasonable to expect the net transfer of heat to be into the room as opposed to out of it, so long as the air more or less remains in the room and does not undergo significant exchange with the cooler outside air), and the air continued to get hotter because of it.

(Change in) temperature is only equal (and even then not dimensionally) to heat when the mass and heat capacity of the two systems being considered are equal, which is obviously not true here.

The change in temperature does not need to be equal to the heat added or lost; a single quantity of heat would raise the temperature of the air by a larger degree than it would the temperature of a human body, but the human body's core temperature does not need to be that much hotter than normal (anything higher than 105 F for an extended period of time usually results in tissue damage and death; note that this is just more than 6 degrees F, or roughly 3 and a third degrees C) to die.

It would appear that the treatment of heat and change in temperature as interchangeable has been confusing a lot of people. I had assumed that people would have implicitly understood that adding heat to a human body = raising body temperature by much less than if the same heat were added to air, because this does not make the argument any less sound, since, as I just pointed out, only a (relatively) small change in temperature is needed to overheat a human body (and because the human body is much less than 100% water and is composed of tissues whose specific heat capacities are far less than that of water, the heat required to overheat a human body is that much less than the heat required to raise an equivalent mass of water to the same temperature).

Fan death, like many other to-and-fro arguments over pointless musings such as "Is there a god", is all just a pleasant waste of a lifetime arguing over something that can be satisfactorily resolved with this reasonable answer:

There is a huge flaw in your reasoning, you are totally wrong about how sweating cools the body down, it cools the body down by evaporating, not by cooling the air around your body. If the fan causes the evaporation to happen quicker that would cool you down faster.

I'd like to point out that the EPA pamphlet doesn't say anything about lethality, merely that it can lead to increased health risks.

I can understand the science behind this, and I'll admit is a possible scenario, but it's really, very unlikely. For elderly, infants, and people with major health risks, it's dangerous because it can cause complications with other conditions. But for a healthy adult? A closed room with a fan is not the same as a convection oven - it'd need like a perfect combination of factors to be deadly. Discomfort? Yes. Dehydrated? Yes. Headache when you wake up? Certainly. You might even head to the hospital - heat stroke can get bad. But actual death?

Here's the thing. 1) People report this happening with air conditioners in closed rooms.2) People report this happening on days without extreme heat (consistently 90 degrees Fahrenheit or above).3) You rarely hear of anyone being hospitalized for this - they seem to end up in the morgue.4) There are many places in the world with similar or worst heat that don't report this phenomenon.

And lastly:

If you found someone dead in their sleep, drunk to the point that they never shifted or awoke in response to extreme heat discomfort, what is more likely? That they were cooked alive by convection ... or that they died of alcohol poisoning? Or vomited and choked?

When a young person is found dead with no apparent indicators of their death, the media tends to report fan death before it's actually confirmed. Fan death is not an official cause of death in Korea and these mysterious deaths do sometimes get autopsied. Inevitably, the cause of death is more realistic, if not less tragic. Alcohol poisoning and drug overdoses are often the result. Occasionally, it turns out to be an undiagnosed condition. The media rarely reports retractions in these instances.

I'm American-born, but I don't hate Korea. I'm not ashamed of it - very few of the Korean-Americans I've met are. In fact, we probably tend to over-idealize it as our distant motherland. If anything, we're thinking that Korean-born Koreans are looking down on us.

And I don't think any less of Korea because of fan death. Honestly, yeah, I think it's kind of a silly thing to believe. But every culture has their urban legends and myths and believing them doesn't have anything to do with intelligence.

The thread is now so long that I simply can't invest the necessary enormous amounts of time to comb through it. I won't repeat the very valid thermodynamic objections (evaporation=heat reduction) that were made, nor the rhetorical ones "Fan death = heat stroke". I think also it is well noted that this is but one of many urban legends compared to many hundreds in the US and 'the west'- but like many from 'the west', I guess I find it a little interesting that it is so WIDELY believed and has the backing of many media outlets and even so-called experts. Sort of reminds me of leeches, which, when they were too popular and a cure-all, actually did more harm than good- but now that they are better understood, actually are quite powerful therapeutic agents.So it has all been said before- but what I really wanted to add is the best theory I've heard of the origin for the urban myth- a friend speculated that it came about during the industrialization era of Pak-Cheong-Hee, when government completely controlled the press- spreading such rumors through media might have the desired effect of saving the nations electricity for industry- not just at night time when it would not be such an issue, but also it would stop those housewives from napping with a fan running. The fact that air-con seems to be immune to this myth sort of chronologically backs that idea- though I'm sure it also backs your 'turbo oven' idea. Once one accepts that most of these deaths are stroke-related, then we have to ask, "is it confirmation bias on the part of Korean investigators, or do western homicide investigators miss the common clue of a running fan?" I'm going with the former, but as you point out, without any scientific attention to the issue it's all speculation. Kudos at least for the thought provoking discussion.

I love your posts, but your science is not really science. As much as I take you as a notable source of information - you are no scientist. I guess if you wanted to create the right conditions then fan death could be possible...but it is highly highly unlikely.

Additionally, if you were to stick a person in a room as hot as an oven, then it is not the fan I would be worried about...but rather that you are in a room as hot as an oven.

I hate to be critical, but this post is written more like...you already had the idea that fan death can kill, and you just went out and tried to find information to fit that idea. You could do that with anything and it seems very unlike you and youre regular posts.Just my two cents, still love your blog - take no offence please.

I have to agree with noe^ and other people. It is nearly impossible for a fan to kill you even in a closed off room. If you could die with a fan on, then you were probably going to die with it off. You actually produce less sweat when the fan cools you. The fan cooling you will cause you to sweat less and not cause dehydration.

You relied on these ideas: "Humans maintain body temperature by developing a thin layer of air around their body that is similar to their body temperature... But if the fan runs directly on the body, that layer of air is taken away, replaced by the same hot air in the room. The room temperature might remain the same, but the body will feel hotter."

But I don't think these are true facts. How can a body develop a layer of air that maintains its temperature? It is thermodynamically impossible for the body to maintain a layer of air around it that is significantly cooler than the air in the room. Reference please???

If Fan Death was real, why is it not believed in other countries? You mean to say Korea is the only country where people have died from this? If it was true, other countries would recognize it and they would also publicize it. Furthermore, not sure if you covered this in the article, but if someone was getting "baked in a turbo oven" as you say, wouldn't they wake up from the discomfort before they die? Or are all these fan deaths occurring with severely drunk people??? Despite your long well thought out answer, fan death is BS. I'm not a doctor, but Korean doctors have said that it is impossible to die because of a fan blowing air on you as the main cause.

While a fan does contribute to dehydration and increased body temperatures, has there been a scenario where the presence of a fan was the main cause of death? In a situation where a person would die because of fan death means that person was in a critical state where the presence of a fan wouldn't have been the main cause of death, and that person would've died of dehydration or hyperthermia anyway.

I don't know what to say about this except that I've never seen anything like that ever happen before. It sounds very far fetched but I think every country has something like this. In Brazil, people believe that if you eat something cold like an ice pop, ice cream or even have ice in your drink during the winter it will give you a cold. I grew up in Massachusetts and the winters are ridiculously long and cold there. People eat cold things continuously there and never really think twice about that giving them a cold. It's only a coincidence because in the winter flus and colds are very common since we are cooped up inside and sharing germs. We all know that germs and bacteria are what cause flus and colds not cold weather because you can in fact catch a flu in the summer too. Maybe the fan death thing in Korea is just a coincidence too 90 degree weather can kill frail individuals it happens a lot here in Georgia and 90 plus degree weather is very normal summer weather here.

Just wanted to let you know (if you didn't know already) that this article has been mentioned in Ken Jennings' (yes, the Jeopardy champ) "fan death" article on Slate: http://www.slate.com/articles/life/foreigners/2013/01/fan_death_korean_moms_think_that_your_electric_fan_will_kill_you.html

Haha, my parents who are Korean told me (it's really hot here in Australia at the moment, sweltering) that I shouldn't leave a fan on while I'm sleeping, or at least not one that blows air continuously directly at my face or body, because this could cause my face or a body part to become painfully stuck in one position. So I googled 'fan myth' when I got home, I had no idea it was death I should be expecting, not temporary paralysis! My parents have never mentioned fan death to me, I'm going to have to ask them about this when I see them... I wonder if there are any other variations on this belief, and why fans are believed to be the cause?

Even if there was a minor possibility of fan death occurring in a certain set of circumstances, that doesn't quite explain why the belief has become so widespread/common knowledge? It would be more plausible that initially another cause of death (more easily achieved than with a fan) was blamed on fans. I'm just curious because this is a weirdly fascinating facet of Korean culture I've never come across hanging out with Koreans or visiting Korea (until now that is!).

I can appreciate wanting to take head on idiotic racists, but I feel this is perhaps the wrong way. The conditions you present may be technically possible, but they aren't even close to plausible, especially in relation to how prevalent the belief is and how many deaths are attributed to it.

Rather, a much better avenue of attack would be to point how cultural knowledge that is easily scientifically disproven are not in any way, shape, or form indicative of a lack of critical thinking or stupidity or anything of the sort. They are present, for the most part, in all cultures. Compare similar cause of death beliefs in America (Don't eat within 30 minutes of swimming or you will get a cramp and could drown!) or even silly things like a widely held belief that sugar causes hyperactivity in children that people will still defend with anecdata if pressed.

Scene 1: crime scene, location: apartment bedroom. Dead man lays in bed. Gaping gunshot wounds on the head and torso, massive pools of blood over the sheets. While detectives carefully step around possible evidence, the camera slowly pans over to the corner of the room, slowly zooming in on the running fan. For unknown reasons, it is wearing a butler outfit.

This is a four year old post i know, and i haven't read all the comments, so forgive me if this repeats something already said, but I thought I should point out a fatal floor in the hypothesis which is:The use of a fan would actually mitigate the hyperthermia, and cause less dehydration, not increase it – which is central to your hypothesis.Here is why:1. Basically your body sweats in an attempt to cool itself (we can all agree on that). 2. If a fan IS blowing air on you then the sweat will evaporate more effectively thus, cooling the body (which is what we want). 3. When the body gets down to the temperature it wants to be at it will stop / reduce sweating. 4. If there is NO fan, the body will continue to produce more and more sweat in an attempt to cool itself. Much of this sweat will not evaporate on the body but rather will wet your clothes etc.5. The situation in point 4 will result in greater amounts of sweat (and thus greater dehydration) and less cooling of the body, both central causes of the Korean’s hypothesis.Conclusion.It is very possible that people die from heatstroke, however the use of a fan will mitigate this to some extent and make the likelihood of it happening lesser not greater.

To add to the comment above, a fan in a room is *absolutely* not comparable in *any way* to a turbo fan oven. A turbo fan oven works because there is a source of incredible heat right behind the fan. The fan is thus blowing extremely hot air to the food, making the oven much more efficient in warming it up and cooking it. But a fan in a room obviously *does not* have such a heating source behind it, it is only moving around the air already in the room.

Your post also contradicts itself with respect to the layer of air next to your skin. You're absolutely right that air is an insulator because the layer of air next to your skin does not tend to move normally. What this does is that your body heats up the air immediately around you, making you *warmer*. However if you have a fan you blow away this layer of air and replace it with air that is at whatever the room temperature is, helping to cool you down.

The only problem would come if the air in the room was already hot enough to give you heatstroke/hyperthermia. In which case, the fan might be making things worse by a *very* slight amount and this would only be the case in exceptional circumstances with a completely sealed room where the outside temperature is already close to heatstroke/hyperthermia temperatures. Rooms loose heat *very* quickly!

In my opinion, belief in superstitions is harmful. I seriously and sincerely doubt that all Koreans have the approach about fans that the author described. If Koreans said "Just be careful about using a fan in a closed room when it's very hot while you're asleep, it could dehydrate you or cause your body temperature to get too high", I don't think we would still have the "fan death" phenomenon. The truth is that there are first-hand accounts from people even in these comments who state that Koreans they know well do believe that fans can kill because of some patently false mechanisms involving oxygen molecules. "Fan death" is often about suffocation, etc., not dehydration/hyperthermia. I'm sure the US and the UK have just as many stupid cultural superstitions that I mock readily. "Bless you!" when you sneeze? My co-workers do it multiple times everyday and I just have to be polite and thank them, but it's a completely antiquated and supertitious ritual. I don't condone that, "fan death", or any other type of unfounded belief. Sure, a fan could prove dangerous in certain conditions, but there are many more conditions when they would not be dangerous, and based on what I've read, I am really not convinced that Koreans are happily sleeping with fans on them in spring/autumn without worrying because they know the mechanisms behind what could potentially make a fan a health issue.

The weather channel video doesn't take into account the fact that even in 95 degree weather, you can have a much lower dew point--which means that sweating will still cool you off. Stay hydrated and know the symptoms of electrolyte deficiency, and you can sit in front of a fan all you like.

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The Korean is a Korean American living in Washington D.C. / Northern Virginia. He lived in Seoul until he was 16, then moved to Los Angeles area. The Korean refers to himself in the third person because he thinks it sounds cool.